Ok so I just installed my rear section on the 91 hf i just bought last week. The exhaust has a leak it looks like the old midpipe is missing a tiny chunk were it bolts to the rear section in between the gasket. Its getting dark so I will screw with it tomorrow maybe the gasket it off or something but it has a leak bad.. here is my question, I was going to take it to my exhaust shop to have 2.25 ran anyways but now I might be a little quicker. Its the stock motor now but am putting in a zc soon. Now the hf has the cat on the header thats it. So if I have the 2.25 piping ran from the header to the rear section, wheni put the zc in is the dc sport header or whatever I use going to line up to the midpipe? and if so that will mean I will be running no cat besides emissions will that help or hurt? Also I would have to have it ran liek that now or else the exhaust shop cant legally run it with no cat right?

 

and i was wondering if the reason it is leaking could be because the rear section is bigger piping than the hf stock midpipe?

 

My HF came with the cat after the header. If you get your exhaust made now it will bolt up to the header w/no cat. I''m assuming its just like 96-00 DX vs EX (built in cat and after header cat) Overall the headers (exhaust manifolds) on the 2 models are the exact same length, one just has the cat in the manifold, the other after the manifold. So on the DX you bolt up a header running no cat, the EX bolts up to the cat

 

running with no cat really does nothing for performance unless the cats clogged.

 

yeah i talked to my cousin who has built a few zcs and who is doing the swap with me.. he said i want to find like a crx si cat and then when we do the swap buy the header dc or whatever and put the cat on the end of it then from there back run 2.25 to match my rear section.. he said it needs the cat i guess for backpressure so now i need to find one of them too. thanks