headers

I might be getting used TOG headers and a down pipe for my stock 99 gtp. Would that require any PCM tuning? I think i heard something about that in other fourms. I also plan on getting the 3.5" pulley at some point with proper supporting mods. Are headers necesary to support a 3.5? Also, will headers alone make much of a noticable increase in horsepower? What do you guys think and thanks in advance

Make sure you get the right downpipe specifically for TOG headers.

Headers are one of the best mods or bang for the buck, however, to get full advantage you should get a reprogrammed PCM module (ZZP, DHP, Intense, or Milzy). Also, headers are not really needed to support a 3.5" SC pulley.

Be sure to check for any knock retard (KR) before and after mods.