My car has a really bad exhaust leak somewhere on the driver's-side manifold. I have a brand new set of SLP's stainless dual-cat manifolds laying around and I came accross a dual-cat y-pipe for cheap. How big of a deal will it be to change it over. Is all of the emissions stuff the same? I'm not trying to get any performance gain, just trying to get my car to not sound like a steam-locomotive. I tried searching but couln't find what I needed.

Thanks alot