Well this is what Im going to attempt to put together on my 85 IROC. http://www.top-downsolutions.com/pow...no-don-headers and http://www.summitracing.com/parts/WLK-17554/. I have dons headers on the car now, and the car sounds amazing for just headers. The build is a 383 HSR xfi292 AFR210s. Just looking for input on how it might sound and maybe the best location for muffler, I was thinking the stock cat location. Yes I'm aware Dyno Dons Y-pipes are 2.5in and the Dynomax is 3in so I also bought 3in to 2.5in reducers for the Y-pipe to muffler. After the muffler Ill have the two 3in ran over the axle to bumper, not sure of what tips yet. I think this would count as a true duel setup? Any input would be great.

 

Just FYI, I have made a point of crawling under a number of new cars that put out over 400 HP, and this is a recurring theme:

Small pre-cats as close to the exhaust ports as possible. Larger cats somewhere in the middle, and the mufflers as far to the rear as possible, exiting directly into the tips. I would think that if this was just for the sake of packaging the exhaust system on a specific chassis, it would not be universal from Corvette to BMW to Nissan to Chrysler. They all follow this pattern, put out a ton of power and pass smog. Copy what works...

TA