from another Prelude AutoX'er, but running SM...
they have a street tyre class for stock cars in your region? double check your local rules, since there is no separate class for tyres in stock classes at the national level.
if your region allows, go with R compound tyres. i know it's acceptable for any stock class car to run R compound. the only requirement is they remain DOT legal. Kumho makes two sets, the Victoracer V700, and the Ecsta V700. both are treadwear 50, DOT legal tyres, for race day only. they have enough grip to shave 3-4 seconds off your times.
urethane suspension bushings are also allowed. this will tighten up your car and make it more consistent thru cornering.
go with a good coilover strut system. Tein makes one that just can't be beat for bang/buck ratio. the Type-HA are 16 way bump and rebound adjustable with coilover adjustability, and rebuildable for custom valving. if you go this route, be sure to cornerweight the car for more neutral handling.
as for anything else, especially power increases, you're pretty much screwed
