Went to sync AEM with the timing gun and noticed. The car was firing on TDC-the white mark. Went to sync the EMS with the red 16 degree mark and motor began to run as though the timing belt was off. The timing belt is on perfectly. While the motor is running on TDC it runs great, but breaks up up top when in boost. Would using an LS crank pulley affect syncing ignition timing. Why will the motor run well at TDC and not at 16 degrees-red timing mark. Any help would would be appreciated