I just bought an 89 civic SI that is need of catback exhaust. I tried searching, but that isnt working. I have 3 questions:

1. Is there any difference between the exhaust on a dx and a si, like exhaust daimeters or the muffler? (If anyone knows where I can look that will give me all the differences between the si and regular civics I would greatly appreciate it.)

2. What is a good place/company to use for exhaust? I looked at some of the stuff on eBay and the stuff Summit sells. I heard bad stuff about the Summit/Monza catback. The exhaust on ebay all seems to be no name, anyone have any experience with it?

3. Should I try to buy a catback exhaust, or just find the intermediate pipe and just use an axleback setup? There seems to be a larger selection of axlebacks than catbacks. Does that mean that the stock exhaust is fine until the axle? I also need to know if I can use any intermediate pipe or only one off of a si, which is basically what question 1 is about.

This is my first post here and any help is appreciated!