I have full boost at 4.000 ish rpm 2 bar t34,with a bigger housing than yours i recon you have a miss match as they have said.
I have no lag at all as i change gear i have full boost always thats what i rate as lag anyways not the rpm it reaches full boost at.
My .48 was ok too not that dissimilar to the t34 etc.
The .36 was out of puff at 6200 drove like my derv mondeo