Crower 2s are about the best mod for the 420A, imo. If you've got the hardware to support them, they would go superbly with a mild street port on a street car. In fact, I might go so far as to suggest my ideal street 2GNT build list:

- Ebay shortie intake w/ K&N or AEM dryflow filter.
- Crower 2 cams, required lash adjusters/followers (w/ Fidanza gears, if budget allowed)
- Pacesetter 4-2-1 header (in the absence of a true LTH)
- GST catback
- UDP

That's where I would call it a day. My next step up would be very mild headwork (mostly clean up, port matching, etc.) and a bump in compression via pistons.

My recommendation for all out race? See bullettdsm, above, add ITB set up, maybe improved, 2nd generation LTH w/ merge collector consideration.

Then supercharge the sumbitch.