I spoke today with Garrett Australia and they said that running a 66mm comp. wheel instead 61mm will have 300-500rpm i will be able to run same power ,but on 3-4 psi less.
Does this make any sense to you?
My intercooler i dont know the brand it came with the kit.
What do you mean meth?Are you talking about water injection.
At this stage im not chasing big hp im happy with my setup,ive just would like to run same power on less boost,its a new engine and more boost just will take the life of it quickly.
Ive ran it down the quarter mile and ran 11.3 at 124mph not bad for a small turbo.

 

Wow nice times!

Meth = methanol injection (like water but meth adds octane and explosive force).

3-4 psi sounds like a lot, but they would no better than me