Random Tech (and clones) are direct bolt-ons but very expensive. Check out Catco brand high flow cats (bought mine from Summit Racing). They are universal fit and will cost you a couple of bucks at a muffler shop but well worth it.
www.ILPperformance.com can build you "anything" you want. They use Magnaflow ceramic cats, stainless steel piping, mandrel bends, O2 bungs. Nice guys, however I didn't buy from them, instead I ordered the Random Tech from Nino which has a metallic cat.