EFR7163 Turbo kit for AWD MQB. Arguably the best overall for spool/efficiency. Retail is $5000USD/$7500CAD. The fit and finish is second to none.
Kit comes with turbo, all oil and coolant lines, APR DP (you need an APR midpipe or to get the center section welded)...
No one here has mentioned the obvious. Any slight misalignment of the outlet pipe can create a small boost leak which would send shaft speed through the roof. That is the most likely culprit to be honest.