I ran a VF24 with the STI ECU on my 99/00 WRX.

Ran like a rocket. The VF24 very, very was quick to spool, and held boost all the way to 6500rpm

Its ball bearing so it spun like a dremmel.

I ran 17 psi boost all day, everyday. Big intercooler, 3 inch turbo back exhaust. No tune required if running the STI ECU. There is so much information out there (and on this forum!!) about running an STI ECU on a 99/00 WRX.