downshifter, do some searching... that topic has been covered on every car forum in existance.
as for the name brand SRI, just make sure its all mandrel bent piping, and that you have a good filter. Its just a tube, as long as its the same diameter, same type of bend, and goes to the same place there is no way an AEM sticker increases power. Look around for a tube, and then get a K&N filter.
if you were getting a CAI, i would lean more towards getting the AEM piece, since its a more intricate part.