my 4x4 used to run a stage one chip just with 500 intercooler and it made 276bhp @15psi but the injectors were over there limit and it was going lean high up the revs round 5500. bought the stg 3 stuff and fitted it and the car made 337@18psi. so to me st3 is the way to go and thats still on a t3 turbo.