Need to know which exhaust manifolds I need

[jmgtp]

This is for the 3500 LX9 going into my 91 Grand Prix. The LX9 manifolds don't fit in the car right so I am looking for 3100/3400 manifolds.

The two things I need to know:

1) what year W cars with 3x00 would place the downpipe in the correct location for my Grand Prix? From what I've seen on ebay it looks like the newer W cars place the downpipe more towards the middle of the manifold then off to the flywheel side.

2) Do all 3x00 exhaust manifolds flow the same, or have the same sized ports? in other words would the manifolds from a 95 flow just as well as those from a 2000?

this is one of the last keys to the puzzle to get the swap done.

[bszopi]

http://www.domesticcrew.com/installguide.htm

Scroll down to step 12 to see different styles of 3x00 exhaust manifolds.

[siKKa]

im not sure the of the down pipe the grand prixs used, im using the 3100 small port down pipe and manifolds from my old 95 corsica in my cavalier, the small port 3100 manifold porst are a weee bit bigger then the 3500 exhaust ports so im using them till i get time to make my headers. for day to day driving they should be just fine.

[jmgtp]

I went with a 3100 rear manifold from a 95 or 96 Grand Prix. Should put the downpipe in the right place.