i have oneon the 1.8litre... made a huge differance... but it spools almost intantly..... onthe 2.5 it is just too small... you should pick up like a Mitsu 16g.... or a t3/t4

 

You could always get a IHI Version5 and up turbo for around $400 from Japan. Plenty of air flow and spools very fast.

 

The stock WRX turbo wouldn't be bad for low boost applications, like say 4.5 lbs. Stock the turbo is set to I think 6lbs of boost. If you went with this route I would recommend a boost controller though, because the boost falls of at redline, so a boost controller, would help with that. Anything over 4-5 pounds wouldn't work out that well, because the turbo becomes inefficient with the increased cfm's from the RS and high boost.

-Wes

 

You cant lower boost below the spring rate with a boost controler. Unless you'll looking for a dirt cheap setup, the wrx turbo is a poor choice for the ej25.

 

i am putting an IHI VF30 on my EJ22 t block and EJ25 SOHC head motor! We'll see you that works!
adamsrs

 

True, you can't lower boost below the spring rate, but you can remove the wastegate spring, and use the boost controller for lower boost.

-Wes