Thanks will, just an update i drove it last nite and this morning upto about 4/4500 rpm and there was no stuttering last or this morning???
Im going to contact my turner tomorrow with what you've mentioned and see if i can get it sorted.
I found the only way I could replicate the problem when I had this "judder/stutter" was to go along a dual carriageway at a reasonable speed and just drop a gear and floor it, that causing the revs to shoot up and hit the boost limit.
If it hits the limiter it will make that stutter/judder.
However please keep this within reasonable limits, don't drop from 6th to 3rd for example!!!
Don't blame me for blowing your engine ^^
Hope this helps
Will