A mate has a mps3 - awesome car!
We were pretty much neck and neck on a launch, rolling run he drilled me (ive only got a cat back and pod - std boost)
They run 15psi from factory - if you want more boost you will need a bigger turbo
The MPS6 i am looking into as my next car - we have a sp23 at home and while its not the fastest car around its a very nice, smooth and comfortable drive.
From what i have read on the mps6, they like to oversteer and stock they put out around 150kw atw - not too shabby!