I am trying to get my hatch actually legal and I need to pull the turbo and downpipe off my 90 Si and put on a stock header. I found one recently and it is from a 88 Dx. Last time I tried putting on a stock header, it was too short. Do you think this is because there is a slight difference between the 88-89, and 90-91 or do you think that because mine is MPFI, the DPFI is too short?

 

To short as in how? If its to short to connect to your exhaust it's because your car has a turbo set up on it and it will not bolt up to your exhaust because the pipe is shorter. And I believe all 88-91 manifolds(no headers because they are the stock cast) are the same. Correct me if I'm wrong.