What size? 2.5 inch or 3 inch

[67thunderchicken]

Vehicle is 67 firebird, 455 motor, Doug's headers, how does the 3 inch exhaust fit into the car --specifically, exit in the stock location. I prefer to use 3 inch rather than 2.5 inch.
Thanks for the help

[Magntik]

I went with 2.5 on my '67.
Only area I would check first is the exit point of the tailpipe.
It's real tight between the leaf spring and 1/4, especially if you plan to dump close to the factory locations like I did.
It doesn't come into contact with either the leaf spring or the 1/4, but a 3" probably would.

[dhardison]

I installed a 3" MagnaFlow stainless exhaust kit on my '70 Nova with the factory tailpipe exit location. It fit great with room to spare between the leaf spring and lower quater panel (1/4"-3/8"). The same kit for your Firebird runs $624 from Summit (MPE-15899), but the thread below will save you some money over Summit's price.

https://www.pro-touring.com/forum/showthread.php?t=28338

[Steve68]

Dans how that system sound?

I have the 3" version Flowmaster, with Super 40's 2 chambers, so it might be a little loud,

[dhardison]

Dans how that system sound?

I have the 3" version Flowmaster, with Super 40's 2 chambers, so it might be a little loud,It has a very unique sound, NOTHING like a Flowmaster kit. If I had to compare I'd say it has an exhaust note like a Corsa or Borla system.

[Steve68]

I'm changing the system, I'm putting a X pipe in the system and getting rid of the H pipe, crap, so it should sound different,

[Hawaiian turbo]

I have the Flowmaster 3" exiting the stock locations, and I'm lucky if I have 1/4 on each side. I made a little dent right where the leafspring would contact the pipe. You can't tell unless you're under there, but the banging was driving me nuts!!!:seizure:

[chicane67]

3.00 fits fine.

I would run the same size as the collector...

[Flash68]

3.00 fits fine.

I would run the same size as the collector...

Chicane- is there a big issue with running a small exhaust pipe than the collector size? In my case, I have a 3.5" collector and plan to use 3" pipe...

thanks