3 inch or 2.5 inch exhaust
 

I've received conflicting advice. I have a 396/402 BB, I've been told 3 inch is the only way to go for a BB. Others have said 2.5 in for correct back pressure.

Thanks in advance.

For performance, 3" without a doubt.

I was "told"... more than 383 ci, go with 3". Or ANYTHING supercharged/turbocharged needs 3".

I've also read that 3 inch to the mufflers with 2.5 tailpipes is fine.

Supposedly, flow isn't affected much by the smaller pipe after the mufflers and 2.5 is a lot easier to bend and package.

I've got a tri 4-bar in my car, so I may go this route...

Jason

Manderal bent is the only way to go, If it's less than say 450 hp 2.5 will be fine. over that I prefer 3 inch

Depends on how pumped the motor is. If stock I would go with 2.5 inch or even a mild motor. If the thing has a large duration cam, good set of heads and header go with 3 inch.

check out the latest issue of car craft there is a great article on this very topic with dyno testing proof.

Car Craft just did an article on 2.5" vs 3.0" exhaust this month. The motor was a 500HP 383 Chevy. Both systems were Flowmaster mandrel bent with Super 44 muffs. Peak for peak there was only a 3HP difference between the two systems. But in the mid range there was a 10hp/10tq gain at a few rpm points. So it at that power level if you have a really low car or dont want a bunch of noise the 2.5" mandrel system with high flow muffs can work really well.


Dang...you must of typed that right before me!

My Camaro has a 3in X pipe into 2.5 mufflers and tailpipes. This is with a supercharged 355. I've had fitment problems in the past, worse when mini-tubbed, with 3 inch tailpipes. I did a lot of searching before I bought anything. I think this is the best compromise. I don't think it gives up any noticible power. It's also quieter than full 3 inch systems. When I'm in boost that's a good thing.

I would do 3"


LOL, we have 3.5" on a turbo V6. from turbo to rear bumper