[Topless in Cali]

I highly doubt S1 for '05 will work on an 03'. I have the early 05 w/ alum intake and my S1 instruction sheet says 235Hp @ 4900 and 275lbs TQ @ 2800RPM. So the difference is in the programming. The plastic manifold will make a difference once you start upping the mods and boost, but I'm not convinced that it would make a lot more power on say an 03 w/S1 and cat-back system. Az, you've got a lot more than that, so I think the manifold will help in the overall power production. Besides, if you go PPQ, the S1 programming is all but irrelavent when it comes to AFR's. Wether or not it is 03 or 05 S1, the programming is altered for even more power!