If i have my boost controller set at half, it will rev nice into the red in all gears!

If i have boost controller set on FULL i have a severe flat spot / lack of power at 5.5K revs.??

Has anybody got any idea's, Jabba looked at it and changed the N75 valve, but i think and can not be 100% certian that the boost controller was turned down and i did not notice. So i thought it was cured.

I must point out that i very rarely run on full boost and did not turn it up and have a serious play for maybe 6 months after it was mapped. So this may have been a problem from day one perhaps.

sounds like a possible air mass metre to me.

sounds like a possible air mass metre to me.

There were no errors showing on vag com?? I am willing to try anything as its really pants.