Hi, I've an '85 535ia, and would like to source new downpipes, since I believe mine are holey, and I need a new cat/exhaust too. I know that I once have seen a site while looking for cats which had a diagram of each exhaust part and even a part number, but I can't find it among my favorites, and randomly searching peoples' sites for exhaust parts hasn't worked yet either. Does anyone have either the part numbers for this or links to sites displaying them? Thanks for any info, -Brian