If you're just going to the autocross to have fun and practice your skills who cares if you're in a way too high class? Power isn't what wins autocrosses anyway.

Maxrev, RevHard and Drag are alright kits, reasonably complete although either one has parts that I would change out. And of course they can always be augmented with programmable ECUs, upgraded fuel systems, etc. I would call them good starting points.

The GReddy non-intercooled kit is good if you live in California and will allow you to shove the "CARB Exempt" sticker right in any cop's face who pulls you over. The kit with the intercooler is a bit on the pricey side but as a total bolt-on, no tuning solution I would say it's the most complete.

If you plan on making the car a bit of a project and don't mind more than one phase of tuning (getting the thing running, switching over to a programmable ECU, etc...) then a Drag, Maxrev or RevHard kit with a few additional pieces will serve you well. If you want a turbo and just want to bolt everything up and be done, no more tuning, I would go with a GReddy intercooled kit.

If you're in California and/or cheap or lazy, the GReddy non-intercooled kit will make more power than i/h/e.