Hi I've got a 2002 wrx estate it's got a full cat less exhaust, cat less turbo pipe, induction kit, dump valve and been remapped, I've been offered a TD06 20g turbo at the right price, just want to know can I just swap this for my old turbo, get a remap and it's good to go? If so what kind of gains in power should I expect, do I need to change anything else?
Cheers

 

With the mods you got I would say it'll be rather rather laggy. You'd need sti injectors, updated fuel pump. Sti intercooler and possibley decent up pipe depending on what you already have. At the very least

Reworked heads and headers would help too

These are huge. can put you in the 400+ club with supporting mods but full boost would be 4.5k upwards. And boost rather late in the rev range! Rule of thumb choose smallest turbo for your power goal.

IMO I'd do the sti bits and TD05 and map.

 

http://www.andyforrestperformance.co.uk/58901.html


http://www.racedynamix.co.uk/remap/subaru-remapping/typical-upgrade-path-newage-2-0-wrx/

Some light reading here to give you and idea if your looking for more power.