well, with the airraid you are already in the hole as far as a good investment for performance. Of course, it does not really matter if you are talking about the crappy intake or the spacer they sell, they both suck.
good upgrades include an intake that is not a hot air intake
99+ intake manifold
bigger downpipe
high flow cat
cam
stroker
turbo
blower
nitrous
most of the things they sell in quadratec are gimmicks