ecu- 1500 installed . power fc or other (roughly)
set of injectors 1100 installed (roughly)
higher flowing fuel pump. nismo/ tomei. whichever 700 installed
4k budget wont do it.
gt3540!! 2 grand. will get you 400-450rwhp easy
oh yeah your gonna need a damn good clutch. theres atleast $1400 installed there.
do it right and dont go cheap
if you only wanna spend 4k dont set yourself such a high power figure. assuming this is at the rear treads ofcourse
hope this helps