Hello people, i'm a Gti-R owner Go easy on me though cos i love cossies

Just posting this on behalf of a friend thats just bought a rwd sapp. Its got a pipercross cone filter, scorpion zorst, stage 1 chip, and light greens.

The boost had been increased using a bleed valve but as theres no boost gauge in the car (yet) he turned the bleed valve right down to be on the safe side.

I plumbed my boost gauge into it this afternoon and set it so that it boosts to 15 psi which is stage 1 boost. Thing is it initially boosts to 15 psi then drops back and holds 11 psi, is this drop normal on cossies?

Or should it be set so it initially goes higher then drops back and holds 15psi? I've set it up the way i mentioned above just to be on the safe side and told him to get it rolling roaded.