most headers say that they have a 3 inch tube collecter and i was wanting to know if the stock exhaust would bolt right up to the headers because i have heard that the stock exhaust is 3 inches on a trans am, so that you wouldnt need to get reducers.

 

If your car had the 350 stock, should fit. (assuming shortie headers with a y-pipe) The connection to the front of the converter is a real bear to get loose though. I'd much rather go ahead and get a high flow direct fit cat. converter and make it easy, and sound/run better too. Rear connection at the converter is a bolt flange.

 

Crawl underneath and measure your "Y" pipe. I would guess that it is either 2.25" or 2.5" from the exhaust manifolds back to the catalytic converters. From the converters back it may or may not be 3". Again measure it to be sure. If you have a car that has the dual converter exhaust option, your pipes from the manifolds to the converters should be 2.5". (Assuming they are stock.)

Also, are they shortie style headers, or are they what is known as long-tube headers? The shorties should bolt up with a minimum of fabrication, but the long tube headers will require more fabrication.