I had another turbo fitted and am currenly running my engine in (done 600 miles). The engine is juddering/misfiring at 3500 rmp when the car is accererating on full throttle. I am shifting before 4000 rmp and it is running as sweet as anything but seems to go crap on boost. Is it overboosting and the ECU soft cutting? Is it a fuel delivery problem? I have only recently noticed it as I have just started stressing the bearings (after the rebuild).