I don't know anyone that has done wheel spacers other than possibly @L-N-F.
As for the CAI, keep in mind they don't do a lot for power. The GMPP looses 1 hp up top but shifts the torque curve in the mid range. Not sure how the AEM affects the power band.
(Magnaflow designed the two 2.5" Sky exhausts on my original Sky, put it on the dyno with the stock intake, then put it on the dyno with the GMPP intake and that's where I get my data from.)
However, I loved the sound of the GMPP intake and if the AEM is the same way...and you're okay with mainly a change in sound...then it will be perfect for you.