I have a moderate performance 396 BBC (380-390 HP)with small tube headers and want to install a Dr. Gas "X" pipe exhaust system.

Should I use the 3"x3" crossover to the mufflers and 2 1/2" tails, or a 3"x2 1/2" crossover to the mufflers with 2 1/2" tails? Does it matter performance-wise?

Thanks, Charles

I'd go 3" to the mufflers then 2.5 tails or no tails, just dumps :D

If you have the 2.5" tails use them and go 3 x 2.5 crossover. I just have 2.5" mandrel duals all the way back, If i had to do it again, I would probably go 3" mandrel all the way out or at least run 3" headpipes to the mufflers.

Will the 3"X3" Dr. Gas "X" crossover install close enough from the header to the stock '67 muffler locations so that I wouldn't have to do any cutting, or should everything just bolt up with the clamps, hangers, etc.?

Currently, I don't have an exhaust system on the car (except headers). This will be a completely new system and I have no idea where the old muffler locations were. I want to install the stock 2.5" tails from the mufflers back.

It sure would help if someone could post a pic of the installed system on a '67.

Thanks, Charles

It might help with the exhaust scavenging if you went with 3" to the muffler and 2-1/2" out to the bumper. Use mandrel bent pipe as much as you can. Unless this going to be a stock rebuild I'd put the mufflers where they work best for looks and fit. The bigger the pipe the louder the tone.

At under 400hp you should be fine with the entire system being 2.5" as long as it is mandrel bent. 2.5" mandrel outflows 3" non-mandrel by 30-40%.