Just read all the posts. First of all, I'm in the Motor City & don't know of ANY regular exhaust shops that have a mandrel bender. I know companies that can mandrel-bend exhaust tubing, but they won't work on someone's car. You can buy mandrel bends & cut & weld the system together, but that is very tedious. I have no problem with good muffler shop compression bends - if the shop has a good custom exhaust man. Also, muffler shop machines (Huth or Ben Pearson) are not made to bend stainless tubing - bending 304 or 409 require too much tonnage for most muffler shop machines. Be aware too, there are muffler shops that do the smooth compression bends & will tell you they are mandrel bends. You should use 16-gauge tubing, whether it's stainless or aluminized. NO muffler shops build exhaust systems out of ALUMINUM! It won't take the heat. As far as stainless types, 304 is the good stuff & is non-magnetic, & it will NOT corrode at all. 409 stainless IS magnetic, & it will get rust & corrosion, but not as extreme as aluminized steel. NEVER let anybody use non-aluminized steel tubing to fab an exhaust system with - it will begin rusting overnight. NEVER use thinner 18-gauge tubing even if it's stainless no matter what grade.

As far as diameters, at around 500 HP & under, 2.5" is probably the right diameter. If you are going to be street driving mostly & not at the drag strip, then 3" would probably be overkill & you may lose some low-end & midrange performance. The right diameter system will give the exhaust flow velocity. Choose mufflers that FLOW WELL! I wish I would have known this back when I had my Hemi Charger back in 1981 - I used some stock Chrysler Hemi mufflers from Mitchells & they flowed like crap! I should have used some Walker Redline Z's back then.

STAINLESS PIPE (304 grade) produces a "ring" & many guys prefer the sound & cooling efficiency of aluminized steel. If you want the best flowing stainless oval mufflers on the market, there is no better choice than the Dynomax Ultra Flow stainless with the stock-looking spun-locked heads. NOTHING flows higher sCFM's than them. Good luck. Hey, the place that is going to mandrel-bend a system for you, ask them what kind of bender they use? I'd like to see if they will even tell you.