I drive a volvo 850 T-5 2.3L, Should I get a new high performance ECU first or work with my exhaust? how should I go about in modifying my entire exhaust? I like the ferrita cat-back exhaust IPD offers, but I also want to get a 3" downpipe. I will eventually get both, I just dont have enough money to get them at the same time. So should i get the downpipe first or the cat-back exhaust?