Before my current set up, I went with a Version 6 STI ECU, with VF24, turbo back exhaust, and bigger top mount intercooler. It turned the WRX into a rocket!! I then installed an electronic boost controller and set boost to 17 psi, giddy up!!

The Ver 6 ECU works very well, is cheap, and offers awesome bang for buck! I highly recommend it.

You should be able to find a V6 ECU for $200 or less.