[MRGTO2U]

Hi everyone,
My 68 GTO has a 428 very slightly modified. The exaust question is, it has 2 1/2 pipe from the headers to the Flowmaster mufflers. Now, from the mufflers back to the rear, it has 2" or 2.25" pipe. Does this hurt my acceleration performance? Should it have 2 1/2" all the way back?

Thanks to all!
JG

[WCWhitey]

If you have Jim Hands book read the exhaust section or do a search for his "Strong Silent Type" article. He mentions that very little will be lost if going down 1 size in pipe after the mufflers as temperatures are lower after the muffler. That being said, I would have no problem going from 2 1/2" to 2 1/4" pipe if I had a good set of tailpipes ready to go. But a jump from 2.5 to 2 might be pushing it. Definately do the search for the article, great info, I don't know of anyone who has done such detailed research on exhaust systems. LOL Bill

[Tom Vaught]

Most tailpipes on "A" bodies have been 2.25" after 1965 model year.

Going from 2.5' head pipes to 2.25" tail pipes will not be a performance loss on a 428 or even 455 with a mildly modified engine.

The VOE mufflers that Tom Hand is making for me for my 455 engine I recently installed in my 64 GTO will have 2.25" tail pipes. (It has aluminum heads by the way but uses a fairly small Ram Air IV type cam).

Tom V.