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Discussion Starter · #1 ·
Hola everyone!

I have attempted to search the internet for hours without too much fruit.......so I turn to those on this forum for possible assistance. My apologies if this has already been beaten to death in the past, this 2013 Chrysler SRT8 is brand new to me and I'm just starting to learn about certain things.

So, the exhaust valves rattle like mad when I first start the car. Took me awhile to figure out it was them causing the ruckus.

I clamped them "open" and the exhaust sounds just fine, no rattling.

My question is this: how bad will the MDS (ECO) be if I just get a muffler shop to weld these things in the open position? I can barely tell the MDS (ECO) kicks in while driving right now with a stock exhaust setup

I'm gonna get the rear resonators cut off and some new pipe/tips. I'll probably leave the center mufflers alone for now.

Thanks in advance for responses, even if they are to beat me about the head and neck for asking a dumb newbie question that I'm sure countless others have already been through long ago.
 

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Hola everyone!

I have attempted to search the internet for hours without too much fruit.......so I turn to those on this forum for possible assistance. My apologies if this has already been beaten to death in the past, this 2013 Chrysler SRT8 is brand new to me and I'm just starting to learn about certain things.

So, the exhaust valves rattle like mad when I first start the car. Took me awhile to figure out it was them causing the ruckus.

I clamped them "open" and the exhaust sounds just fine, no rattling.

My question is this: how bad will the MDS (ECO) be if I just get a muffler shop to weld these things in the open position? I can barely tell the MDS (ECO) kicks in while driving right now with a stock exhaust setup

I'm gonna get the rear resonators cut off and some new pipe/tips. I'll probably leave the center mufflers alone for now.

Thanks in advance for responses, even if they are to beat me about the head and neck for asking a dumb newbie question that I'm sure countless others have already been through long ago.
Please don't let an exhaust shop touch your SRT8.

You can just reverse the springs to keep your active exhaust valves open. As far as the sound in MDS mode, if it does ever bother you, you can reverse that mod. There are also kits available to delete the valves. There's no need to destroy them with a torch.

Any pipe a muffler shop cuts off will be made of stainless steel that will outlast the car, and they'll replace it with garbage mild steel that will start rusting on the drive home. Plus, you'd be exchanging smooth-flowing factory mandrel bends for shiatty crush bends.

The resonators are just there to control drone, and I definitely wouldn't cut them off.
 

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Discussion Starter · #3 ·
Thanks CtCarl! I mostly agree with what you have stated above. Thanks a bunch for that link to the spring trick, I seriously couldn't find anything on it....maybe I was just searching the wrong terms. I'm definitely gonna try that right away.

As for the rear muffs.......I have ALWAYS cut these off my cars/trucks with fine results. I want it louder. It never bothered me and certainly won't on this car either. To each their own, but seriously thank you for your opinions and information. (y)
 

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Thanks CtCarl! I mostly agree with what you have stated above. Thanks a bunch for that link to the spring trick, I seriously couldn't find anything on it....maybe I was just searching the wrong terms. I'm definitely gonna try that right away.

As for the rear muffs.......I have ALWAYS cut these off my cars/trucks with fine results. I want it louder. It never bothered me and certainly won't on this car either. To each their own, but seriously thank you for your opinions and information. (y)
No problem. I understand your position on resonators. I won't say the ones on our cars are unique, but they are definitely special, compared to the simple little can resonators I was used to in the past. There's a great article by Bill Visnic, who interviewed Mathias Keck, vice president of development for Eberspaecher North America at the time, about the engineering that went into the original LX hemi exhaust. It's worth a read, but the short version is that lopping off the resonators on these cars will usually lead to drone and/or unpleasant harmonics, especially in 4 cylinder mode. And the truth is, they're not mufflers in the traditional sense, so you won't gain that much sound with them off. And that's where the sharp bends are, which is why I mentioned mandrel bends vs crush bends.

Consider deleting the mid-mufflers instead. They have more control over sound, and it seems like that's what you want. Plus, the mufflers are a "straight shot", it's very easy to replace them with the muffler of your choice (like a couple of bottle-style racing mufflers, just enough to tame the rasp) or even with straight stainless pipe from a speed shop. No bends involved, and as a bonus, no hangers to cut, re-weld, or replace with cheesy, noisy, aftermarket hangers. You can get the sound you want and maintain the quality and integrity of your factory exhaust.

Good luck however you decide to go.
 

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Discussion Starter · #5 ·
Ok, I see your points about leaving the rear resonators. I will consider.

I am now reading others posts from members that have messed with their exhaust systems on non-MAF sensor controlled vehicles, and they are reporting diminished performance because the ECM learns over a period of time and they actually experience worse MPG and less performance afterward.

I messed with those exhaust valves last night per that info you gave above and I could swear the Trans shifting is softer today. Maybe it's all in my head.
 

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Ok, I see your points about leaving the rear resonators. I will consider.

I am now reading others posts from members that have messed with their exhaust systems on non-MAF sensor controlled vehicles, and they are reporting diminished performance because the ECM learns over a period of time and they actually experience worse MPG and less performance afterward.

I messed with those exhaust valves last night per that info you gave above and I could swear the Trans shifting is softer today. Maybe it's all in my head.
Speed Density (which our cars have) vs. MAF does come up a lot online, but mostly as it relates to intake air in general and CAI systems in particular.

I have seen a number of folks complaining about a loss of "power" after exhaust mods. Often, there will be replies from others who confidently explain that this "loss of power" is the result of "reduced backpressure". The truth is, I think, a little more complex.

When you tinker with your exhaust system, especially by eliminating a restriction, you can substantially alter the gas velocity. This can shift your powerband a bit, losing a few HP at the low end and picking them up again at the top. If the change is made up front, where the exhaust gases are hottest, it'll be more noticeable. And that's one reason I've avoided muffler deletes myself. I think these cars are too heavy as it is, and I don't want to trade away one ounce of low-end grunt. So if it were me, I'd be more likely to swap out my stock mufflers for straight-through aftermarket units than to delete them completely.

My favorite LX/LD exhaust trick is to just mod the resonators for a little more sound. The reason I didn't suggest that to you is that I'm not 100% sure that your resonators are the same as mine. I'd have to see them, and do a quick check with an endoscope or length of wire to confirm. And it's a modest increase in sound, you can get more with a muffler delete or swap.
 

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Discussion Starter · #7 ·
I am leaning more towards a couple race bullets in place of the stock mufflers at this point. I do want to hear it more, but doesn't need to be obnoxious by any means. I may replace my tips with larger diameter just for the "looks" department too.

Thanks for all the info, really helpful!
 

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I am leaning more towards a couple race bullets in place of the stock mufflers at this point. I do want to hear it more, but doesn't need to be obnoxious by any means. I may replace my tips with larger diameter just for the "looks" department too.

Thanks for all the info, really helpful!
You're welcome. Good luck with it!
 

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Discussion Starter · #9 ·
Update:


I got two (2) Total Flow race bullets installed yesterday in place of the mid-mufflers. Sounds barely louder than it was with the stock mufflers in place. Wide open throttle sounds considerably better, not loud but proud, if that makes sense. I think I'd like to hear this thing more at startup and while idling in traffic though. Those resonators out back are large and do a VERY good job of knocking down the rumble. I know that the 392 Chargers exhaust systems are considerably louder than the Chrysler's are, by rights and it makes sense. Down the road I'll probably swap out the rear resonators for something smaller and get me some of that rumble.

What I can tell so far is that with the new bullets installed, my torque down low seems to have woken up some. Much easier to spin the tires now than it was with the stock mufflers. I know that messing with exhaust systems can move the peaks and valleys around a bit with the TQ and HP.

My favorite LX/LD exhaust trick is to just mod the resonators for a little more sound.
What's your "trick" Sir???
 

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Discussion Starter · #11 ·
Ok, thanks. I see what is occurring here and doesn't look too invasive.

But here is my question: isn't there someone out there who has gotten rid of the behemoth resonators on these Chryslers and replaced them with something smaller and achieved good results without having drone city inside the cabin with the MDS? I mean, there are a million options for mufflers and resonators out there these days......
 

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There used to be lots of videos on youtube showing what the cars sounded like with the suitcase muffler replaced with straight pipe. But they were the older cars like my 05.
I cut the resonators off my 05MagRT and it sounded great when I stepped on it but the drone at low rpm was too much for me to tolerate so I put them back on.
 

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Ok, thanks. I see what is occurring here and doesn't look too invasive.

But here is my question: isn't there someone out there who has gotten rid of the behemoth resonators on these Chryslers and replaced them with something smaller and achieved good results without having drone city inside the cabin with the MDS? I mean, there are a million options for mufflers and resonators out there these days......
I can't speak for anyone else, I wouldn't suggest you do anything at all to your resonators until you ascertain which type you have, the straight-through variety or the ones that look like the old Microsoft Pipes screen saver inside.
 

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Discussion Starter · #14 ·
I just used a wire hangar and inserted it into one of my rear resonators. It went in a full 2 feet without bending. My guess is that these are the variety that slightly bend through the case rather than "snake" through like your Microsoft example.

Even so, wouldn't drilling into these still provide benefits as far as sound goes? I mean, I plan to get rid of these things anyway for whatever my next idea is back there....so drilling holes in them really won't matter in the long run.

Thoughts?

NOTE: I have been watching a TON of video clips of Charger Scat Pack cars with bullets in the mid location and leaving their rear resonators in place and they sound awesome. No idea if they are manual trans or auto cars because that is never mentioned. Wondering if there is anyone on here who reads this thread that has one of those cars and can attest to the type/volume of drone in the cabin with the MDS on and the setup with mid bullets and rear resonators intact??? If it's not too awfully bad, I may just swap out the huge resonators on my 300 SRT8 for something smaller that would knock down the drone but also allow it to sound cool like it should.
 

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I just used a wire hangar and inserted it into one of my rear resonators. It went in a full 2 feet without bending. My guess is that these are the variety that slightly bend through the case rather than "snake" through like your Microsoft example.

Even so, wouldn't drilling into these still provide benefits as far as sound goes? I mean, I plan to get rid of these things anyway for whatever my next idea is back there....so drilling holes in them really won't matter in the long run.

Thoughts?

NOTE: I have been watching a TON of video clips of Charger Scat Pack cars with bullets in the mid location and leaving their rear resonators in place and they sound awesome. No idea if they are manual trans or auto cars because that is never mentioned. Wondering if there is anyone on here who reads this thread that has one of those cars and can attest to the type/volume of drone in the cabin with the MDS on and the setup with mid bullets and rear resonators intact??? If it's not too awfully bad, I may just swap out the huge resonators on my 300 SRT8 for something smaller that would knock down the drone but also allow it to sound cool like it should.
The Scats and newer 5.7's have straight through resos. They're not much off from glass packs. If the mids are left in place, there is ZERO drone and ANY RPM, even under light throttle, low rpm cruising with mds engaged. With the mids removed, there is a slight (and I mean ever so slight) drone and mds sounds like it's missing a lobe on the cam lol

I have an inner ear condition that makes me susceptible to low frequency sounds, to the point it becomes painful and WILL make me puke if it happens for too long. With the mids removed on my Scat, I wasn't bothered by it. I did turn off MDS because I drove by a friend and he called me to ask what was wrong with my car lol.

I'm well beyond stock now, and my car is borderline obnoxious. Longtubes, catless, summit glass packs in the middle and stock resos at the ends. You won't be having conversations around it while it's running, but inside it's not atrocious. I can hear the radio and have conversations without screaming and there is no drone at all.

I'm shocked how well the stock resos allow sound to come through and keep the drone at bay. To the point I'm seriously considering finding some take offs to replace the resos on my Durango, which has the huge resos like the older 5.7's.
 

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Discussion Starter · #16 ·
Thanks for the feedback Punisher!

I like the sound of the SCAT PACK cars. Their resonators are MUCH different than mine on my 300 SRT8. I'd love to score a pair of the SCAT resonators and just swap. I looked up the part numbers that I found in another thread and didn't seem to find too much in the way of a pair of them for sale, but I know that a lot of folks just cut them off too.

Decisions, decisions.........
 

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Discussion Starter · #18 ·
My guess would be yes since the overall general platform is the same, but who knows. That's not what I'm after here.

Should I reasonably assume that the ONLY exhaust modification that will work WITH THE MDS FUNTION ACTIVE for this model/engine is the mid-muffler delete and leave the rear resonators?

I have already installed Total Flow bullet race mufflers in the mid-muffler location and it's just too quiet for me. The Total Flows have made the exhaust note much deeper by just swapping them for the stockers.

I tried the "trick" of modifying the rear resonators yesterday by drilling a 1/2" hole through right before the tip leaves the case and it gave it just a bit more sound, but nothing like what I'm after at all.

I'm heavily tempted at this point straight pipe through the rear resonators and just deal with turning the MDS off all the time (if it bothers me) until I can afford to get a tuner and tune out the MDS function completely.
 

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I tried the "trick" of modifying the rear resonators yesterday by drilling a 1/2" hole through right before the tip leaves the case and it gave it just a bit more sound, but nothing like what I'm after at all.
That mod doesn't do anything on a straight-through resonator.

I don't think you'll get what you're after by taking off the resonators if they're the straight-through design.
 

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My guess would be yes since the overall general platform is the same, but who knows. That's not what I'm after here.
:unsure:
You said you wanted Scat Pack exhaust noise.....so if all things are equal (the exhaust manifolds & mid pipes), then adding a Hellcat/Scat Pack exhaust would accomplish that (IMO).

I'm not sure what is different on the 300 SRT system.

If you did swap it out, the stock Scat/Hellcat exhaust will have NOTHING to do with MDS.
It won't drone in stock/unmodified form, but even if you wanted it louder & swapped out the mid mufflers on the Charger Scat/Hellcat exhaust with some Vibrants.....there won't be drone when the MDS is active either after that.
 
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