If you're staying with stock turbos, then you will have 4-bolt dp's. Surely you wouldn't go to tp's without changing to dp's. Even the cheapest basic split dp's are a dramatic impovement over those pre-cats. ... But I don't think it matters. I think stock pre-cats, 4 bolt dp's and 5 bolt dp's, all bolt up to the same cats/tp's. I think the diff comes in when you go to 3" dp's.