Washers for bolts or Stage 8 bolt kit?

[06-3.5L DCharger]

Hi,

I will be installing my long tube headers with highflow cats hopefully the week after xmas. I was wondering if I should use stage 8 bolt kit or these washers for the bolts. Or use the Nord Lock Washers.Here is a demonstration vid http://www.youtube.com/watch?v=mgwmuZuJ02I

If I choose to go the Nord lock washers what size do I need for the bolts for the headers?

Thanks

[06-3.5L DCharger]

Anything ?
Anyone ?