Turbo
 

If i changed my td04 on my wrx with a td05 or td05h from an sti would it make any difference in bhp any ideas?

You can't just put a bigger turbo on without a remap

If you got it re-mapped to suit, it would make a difference in bhp, quite a big one.

What year is your car?

TD04 is good for about 300BHP on a 2.0 with wisely selected supporting mods...the TD04 spools up lower rpm and spins up quicker than the more laggy TD05. So there is a trade off. But you can squeeze upto 400bhp out if TD05...again with suppporting mods (or engine goes bye bye)...its not just about fitting a bigger turbo. :)

Car is a 96 import and standard apart from the exhaust but i was gunna get induction kit etc and a re-map after fitting all the extras, so i was thinking about changing turbo before the re-map and get it all done together

Change it yes, but stay of boost and ideally you want it mapped asap.

I take it your car is a WRX wagon then? :)

Tony:)