honestly I would go with F/I right off the bat. The hp gains from staying N/A just seem to be very small for the cost. Try and find something used, you may have to wait that extra time, but in the end you will get the same results with a significatly smaller bill. (Even smaller if you do all your own work)

 

No one has hit 310whp NA...or 305 w/o spending a lot a lot of money. FI would be your answer. I'd suggest turbonetics ST or APS St for your power goals. Your price range is about right for either ST.