My spec is as follows:

1600 cvh bottom end 0.5 over bore
std compresion (mahle pistons)
stg 2 head
285t2 cam
GRS intercooler
stg3 turbo
stainless
k+n

i have completely rebuilt the engine over the winter, it has been run in properly using cheapish oil, i am now running it on mobil 1 15/50 and it has covered 3k with no leeks, knocks or bangs.
My local rolling road guy said it is one of the strongest 1600 engines he has ever set up showing well over 200 bhp, i said of course it is, i built it
But to get to the point of this post, when i rev the car past 5 thou it is loosing power allmost as tho there is a soft limiter before the harsh one at 6 thou. only started recently.
Gonna reset my plug gaps to .7mm see if this does anything for me.
I have tried turning boost right down to see if it is a boost related prob but still there, i have also tried my vernier in about 6000000000 different positions but did not have any affect.
Wonder if my dump valve is leaking under pressure? its a new venturi.

any body had a similer prob?

Cheers, Pete.