Originally Posted by Gregor
Wel.. when i'm doing above 3500 rpm when i'm in next gear i don't expect as much lag as i'm getting (it's not building boost or something, but just staying the same revvs it seems ) ... well anyway... and yess.. i've got a dumpvalve on it....

Take dump valve off and see what happens, i'll be VERY suprised if you don't notice a difference.
Otherwise as said at the top, turbo lag