I was planning to have a simple race exhaust made so I wanted to be sure (1) that it’s legal and (2) that it’s a decent design that will give reasonable performance. I have the cat/downtubes off the car and after looking at it this thing doesn’t look like the other pictures of stock E30 cats. Here are some pictures (sorry for the clutter in my shed… )
This is off of a '90 325is but it’s very possible this is an aftermarket piece. It obviously joins the two downtubes into one large pipe prior to the cat. If I were to use this, as per the rules I’d cut the large pipe immediately before (coming from the engine side) the cat and probably run one large pipe back to a race muffler(s).
(1) Is there any way this would be considered legal? From my reading of the rules, the answer would be no since they say nothing about replacing the cat/downtubes. Normally I’d go to a salvage yard and just grab a stock replacement, but unfortunately selling a used catalytic converter is illegal in California. Supposedly all our local salvage yards remove the cat as soon as the car comes in. Any advice in this area would be appreciated. It seems I’m somewhat screwed here. A new factory piece would be major $$$. :ohmy:
(2) If this particular cat happens to be legal, is there any downside (performance or otherwise) to running one large pipe all the way back versus two? I’ve been reading through the archives and (since most everyone seems to have the stock cat) the most common setup seems to be two pipes back to either two mufflers/glass packs or a two-into-one muffler.
Thanks in advance for the input,
-Joe