Yeah, I don't know for sure if the jets are a different size or not. I just thought they might be, because the pipes are different. I have seen people interchange the pipes, but if I remember correctly, the mounting brackets are just a little off and won't line up. You might have to do a little fab work. I would say that the jets in the '88 model are definitely different, because the '88 model came out with a bigger cam, than the '89-'2000. I figured that might be why they used the different pipe, but if it is they didn't change the pipe until '92. That would make me think that the '88-'91 pipes would flow better, because it's the same pipe they used with the bigger '88 cam, but I could be wrong. Because of the cam, the '88s ran a little better.