Currently in my 2002 my exhaust is filled with leaks and covered with rust, and both cats are most definitely shot which is evident by the fact I've been driving around with a p0420 code for years now. Bottom line is everything needs to be replaced, from the first cat to the tail pipe. The pipes are just so mangled that replacing everything seems like the best option. The dealer quoted me over $3000 to get that done... So decided to just do it myself. I've been on Rock Auto picking out parts and pricing it out but started having a lot of questions that I can't find the answer to. I only recently started doing this kind of work myself and want to make sure I get everything right. Firstly, does it matter what brand of gasket goes with what brand of part? I've only found this diagram for part numbers from Walker, but I don't know if it matters that everything needs to be the same brand. After that I just need to know what bolts and nuts to buy because none of the parts come with them and they also don't say what size is recommended.