[Hemi Challenger]

Do you think that the 3" Cat back exhaust system on a 5.7 automatic Challenger is to big and would it lose HP instead of adding? I Installed my 3" Cat back and the car litterly SLOWED down quiet a bit. Any Info would be helped here. Thank you

 

[Sublimeon24s]

Yes, its too big for the R/T unless it has heads, cam, etc......you most likely lost back pressure / low end torque

 

[charginscott]

^^ agreed ^^

 

[Shane B]

Yes, its too big for the R/T unless it has heads, cam, etc......you most likely lost back pressure / low end torque

x2 definetly!!!!

 

[JBs_300c]

you guys do realize that the new 5.7 heads flow about the same as the 6.1 and the cam is about equal to the spartan? the 3" should be fine. we'll see for sure in about two weeks. i have srt LT's, catless mids, and a 3" srt mbrp exhaust goin on. from my experience with the new challenger r/t really opens up with exhaust mods.

do you have an intake? a guy posted ome results of a header install with before and after dyno. only made 6/6 hp/tq until he changed the intake then it jumped to 20/20. just food for thought. to get more air out you need more air to come in :beerchug:

 

[HEMI~C~]

I agree..... given how much air these motors are flowing I think you could more than justify the 3in exhaust especially when future mods are to be factored in. Stock SRT8's came with 2.75 exhaust and most saw improvements with aftermarket cat backs. These motors aren't your typical old school Small Block Chevy's thats for sure.....many of the old paradigms do not apply here.

 

[Speedlogix Sales]

The 3" exhaust didn't hurt Lisa (BMC Performance) run 13.18 in the 1/4 mile (This was after the 13.5 she ran with the smaller exhaust) before tune and 12.87 in the 1/4 mile after her tune in her 5.7L Challenger

13.52 - http://www.lxforums.com/board/showthread.php?t=138829
13.18 - http://www.bmcperformance.com/forums/showthread.php?t=1368
12.87 - http://www.lxforums.com/board/showthread.php?t=143639

 

[dwhip]

Everybody said i wost lose low end power once i added my 3" exhaust, however it actually took .2 off my 1/4 time with the same mods i had when i had my 2.25" exhaust. One thing i learned about this forum, is if you get one person or a group of people are that suppose to be a experts in something, everybody goes with whatever that persons says instead of trying it out for themselves and making their own conclusions

 

[Sublimeon24s]

He already did try it out, and he stated his car is slower

 

[ChagaRT]

Could it take some time to get used too? I mean my exhuast got better after a few hundred miles.

 

[JBs_300c]

He already did try it out, and he stated his car is slower

weird how it gains 20hp on the rest of the challenger r/t's :roll:

unless hes talking about 3" strait pipes that may be a problem. but the 3" bolt-on cat backs seem to do pretty well on the dyno and track. not sure how good the butt dyno is fairing with the other two tho

 

[Hemissary]

A 3" exhaust even on an 09' will result in losses.

 

[rander]

I had the B&B fat 6.1 resonated pipes that are 3" on my srt stock exhaust. I have 5.7 though. I noticed right away I lost low end torque. I drove around like that for some time thinking it was all in my head. Well, last week, before my fiasco, I put back the stock pipe and reso's back on my ride and lo-and-behold, my car never felt so torquey down low. Glad I made the change. I'm thinking 3" is just too big. You may want to put on an stock srt exhaust and you should be able to pick one up pretty cheap on these forums. I just love the rumble on the the stocker.

 

[stevesrt8]

torque

torque wins races, especially at the strip.

Big pipes kill torque on near stockers.

Read up on Lingenfelter, a man who knew torque personally!

If it's louder it must be faster!

 

[HEMI~C~]

He already did try it out, and he stated his car is slower

torque wins races, especially at the strip.

Big pipes kill torque on near stockers.

Read up on Lingenfelter, a man who knew torque personally!

If it's louder it must be faster!

No doubt torque is king.....put it on the dyno or get it to the track.

Has anyone done a back to back yet (and I don't mean the butt dyno either)....louder always feels slower to me, but typically its a matter of perception which typically has nothing to do with actual performance.

 

[crhemi]

That's what makes cut outs so attractive to me. Best of both worlds.
I took my Magnaflow reso's off and it sounded bad a$$ drone and all, but I felt less power off the line not sure on the top end though...

 

[JBs_300c]

sorry to bring up an old thread or a "i told you so" but heres your dyno results.

base line was with shorties/catless mids/ 2.5" slp LMII exhaust

after with dt's LT's/catless 2.75" mids/ 3" MBRP

just food for thought. this isnt the same motor fellas