If you are getting a 3.4, then you will need to get some kind of CAI and downpipe/u-bend replacement at the least. The Wizaired CAI is awesome in my opinion. Easy to put in, PCM is right there, it is loud, and overpriced. I spent around $230-240 from ZZ and I had to buy the filter on top of that for another $40. If you are sticking with the 3.4 and not going smaller and don't like noise, then get the SLP. It's almost as quiet as stock and works fine with a 3.4. If you don't care about noise, money, plan on using a smaller pulley, and want the most performance then get a Wiz(1), MSP(2), or Thrasher(3).
Jack
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JackO
2004 GTP CompG. WS6, 3.29 axle, HUD, tapshift, Premium sound, XM radio, leather, sunroof, 17inch 5 star chromies, BFG Comp T/A. Wizaired CAI.
Traded in. 2003 GTP. Every option but HUD. New Mods: Wizaired CAI, SLP Headers, Cat, U-bend and Downpipe, 3.2 Modular Pulley, Phase 3 rollers w/OR Pushrods, Larger Belt Tensioner Pulley, Gatorback, AL103's, 180 Degree Stat, DHP