4x4 boost issue
My brothers Saff 4x4 has a little issue with his turbo boost. The car is original except for a 044 pump, exhaust and stage 1 chip. When giving full throttle it boosts to aprox 1.1 bar but then after 4000 rpm the boost starts to whobble a bit. To 1.2 bar and back to 1.1 and up to 1.2 and down again. It's not steady.
Any idea's?