I hear that it is a good idea to get a fuel pressure reg. when you get full exhaust, header back. The reason i got is because the air/fuel ratio tends to run rich because of the new exhaust........
the puter will trim the A/F ratio to maintain stoich. some folks say it helps at WOT (no lambda input; similar to open loop operation and mapping), but the more i read, the more i believe that even this operation is trimmed after some time.