are the reogrammed PCM's from ZZ worth getting if i go with a 3.5 or 3.6, plog, intake, 180 stat, colder plugs, and a little cat back (i know theres not a lot of power from it, its just for a little attitude.) i have easy access to a tech2 to watch KR also which i will do after mods. also will the stock downpipe be ok since it does not have a u-bend?