these are the muffs I used...
http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM%2D633222&N=700+4294923429+4294922711+4294922710+400304+115&autoview=sku
I'm guessing this would be the comparable Magnaflow...
http://store.summitracing.com/partdetail.asp?autofilter=1&part=MPE%2D11226&N=700+%2D43867+%2D44585+%2D44586+400636+115&autoview=sku
...for you guys that have done headers, cams, top swaps, large D/P and/or hi-flow cats...I would think a chambered muffler would be even more vital. I'm sure mine would be a bit louder if I didnt have the Hushpower in place of the resonator...but I think if I go pressurized at any time in the future, I think this system will handle it fine. All I believe will happen is to get a stronger rumble than I have now. I think a glasspack or ZZ's new resonator (in the resonator location) would yield a stronger sound but I'll be sticking with these muffs for sure. I'm glad I didnt spend the extra for Flowmasters, especially since I read on their website that the 40s & Super 40s will have strong interior resonance...no thank you on that. I know we all want a strong sound from our cars but with this engine louder isnt better...and I dont think it has lost any flow, or atleast it doesnt feel that way from the "seat dyno"