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Gunner,
Since you've got S1, exhaust, & intake, you've pretty much maxed out S1 w/o controlling boost. The hard uppercharge pipe, Adam's Pipe, is a really nice addition(I've got one w/o S1), but it my not give you the boost you expect because you've already gotten used to higher power levels with your mods. A Electronic Boost Controller or ajustable waste gate actuator, IMO, for your mods is the best bang on striaght line performance. However, without a set of beefy sway bars you're going to be all over the place trying to get that power down on the road. The eibach's are nice, but for the $$ you're only getting a front bar that is 1, yes 1mm, in diameter bigger. The stock GT front bar is alreay 24mm, the eibach 25. IMO, that is too much $$ for 1mm. I wouldn't put anything less than the Progress 27mm F, or Suspension techniques 1 1/8"F(29.5mm). And they are both better priced than the eibach's. Just adding a rear bar to your cruiser is going to really make a difference and that isn't too costly although you do need to purchase about $70-80 worth of factory parts to do it. If I were you, I would get a full set, F & R, of Progress or Suspension Techniques bars. You'll be mighty impressed with the improved traction and corning ability you're PT will have.
Jaspersnow...
You don't know what you're missing on the sway bars. I think 1ptturbo has this one nailed.
Turbozcs...
The wga/boost controller won't fight the S1 unless you run over 20psi. then it might kick on you. S1 is supposed to be 18psi max. I have read some people are running a spike to 20psi then dropping back to 18 psi without problems. Beyond that you'll need the greddy eo01/e-manage or the psi-fi piggy back to really get more out of S1. Both systems tune your fuel injectors and do other nifty stuff! The turbo back exhausts over 2.5" are overkill unless you go all the way to the piggy back systems since the turbo exhaust outlet is only 2.5"
just my .02...