Well heres the dillema. Im waiting to get a header but my exhaust system is in really rough shape. I have a 12a with the 85' manifold and I was just wondering what the largest diameter pipe I could possibly get attached to the stock manifold now (basically a straight pipe back to the muffler) so that when I get a header it wont be too much more trouble. Is it possible to get a 2" or 2.25" pipe fitted to the manifold or what should I do? I really need to continue driving until I get the header, any help would be great

 

any size you want?!?!? as long as it is about the same as the stock pipe i think you should be fine. But the header with a straight pipe is wayyyyy better than just a straight pipe. I know this from experience.

 

2 inches or 1 7/8 ID? It won't be all that bad either way you go. Just don't go larger than 2 1/4".

 

so will 2.25" piping be able to attach to the stock manifold, or am I going to have to run 2"?

 

You will need a flange like this to bolt to the exhaust manifold.
The manifold has two studs.
If you can still turn the 2 nuts on the studs with 2.25" pipe, and welds between them, then you can use 2.25" pipe.

I cut the flange off the old cat, and cleaned it up.
I also used 2" pipe.