[daduck]

Grand Prix has a factory Pontiac 400 with 6x heads,
Firebird Central has Ram Air D-port exhaust manifolds but does not list Grand Prix as compatible.
I am going to call them but wanted to ask the experts here first.
I am not at all familiar with Firebird fitment or clearance issues compared to Grand Prix.
I plan to replace the entire exhaust system so the downpipe flanges on the Ram Air manifolds being different from stock it is not a problem.

TIA,
Dave

[craig santry]

i have a 1975 grand am 400 and wanting to know the same thing. looking to put shorty headers on

[unruhjonny]

I'd suggest starting this way;
if you still have your original manifolds, check the configuration, and if they are shared with the F-body;
if they are the same, odds are you can use them.

If you have a center dump drivers side exhaust manifold, then those RA manfolds will not work.

[Iggy]

I put a set of Ram Air Restoration RAIII manifolds on my 1974 Grand Prix (2-1/2" outlet) and used the Pypes system and manifold pipes for a 1969-1972 A-Body. They fit well and only minor tweaking.