I don't believe adding downpipes means that you lose your cats. The idea is to get pipes that breathe better (aka larger diameter). The cats could be a source of restriction so many would likely opt for a high flow variant to substitute for the OEM parts. In cars with 2 cats, some people/cars can still get by with only 1 cat installedHey Rob, congrats on the purchase. However, being completely new to car modifications and not mechanically inclined at all, it seems the more I read, the more confused I am. Hoping you can help me out here.
So adding the downpipes removes the catalytic converter, yes? How are the cars street legal after that? Where I live we must obtain an emissions inspection to renew license plates and I don't see how one could pass without it.
Are there viable downpipe options that leave the CC intact or reinstall new ones?
Also, are the secondary cats also needed for emissions compliance? It seems most of the cat-back systems remove these, yes?
I just don't want to be in a position where 2 years from now when it's time to renew my plates, that I have to drop another $2k to bring the car back to stock to pass inspection.
Unless I'm mistaken, what you're thinking of is "straight piping" a car. (which is also achievable by just disconnecting the exhaust system and letting all your gasses leak out from basically under the two front seats how Honda ricers do)