[Tom Pugh]

I am installing a 455 in my '76 GTO. It will be using the Parts Place 2.25" exit HO manifolds ( Ames sells a 2.5" version but they were on backorder. I want to run 2.5" downpipes all the way back to the mufflers. Will there be a problem mating the 2.5" downpipes to the 2,25 HO manifolds or will I need to stay with 2.25 pipes all the way back?

[form74]

I have 2 1/2 inch manifolds mated to 3 inch exhaust.

A short section of 2 1/2 inch pipe was stretched to 3 inches on one end and welded onto the three inch pipes using the 2 1/2 inch flanges

[MatthewKlein]

Originally Posted by Tom Pugh

I am installing a 455 in my '76 GTO. It will be using the Parts Place 2.25" exit HO manifolds ( Ames sells a 2.5" version but they were on backorder. I want to run 2.5" downpipes all the way back to the mufflers. Will there be a problem mating the 2.5" downpipes to the 2,25 HO manifolds or will I need to stay with 2.25 pipes all the way back?

I used 2.5 downpipes on 2.25 manifolds
It was necessary to grind the exhaust pipe to clear the manifold studs

[Cammer-6]

post pics of said 76 GTO

[400 4spd.]

I have a pair of 2.25 flanges if you need some, 2 stud and 3 stud.

[Tom Pugh]

I have the flanges, thanks