The S55 engine is not designed to take a large increase in boost beyond the OEM spec. Due to the design of the crankshaft, it is known to have the timing chain sprocket spin on the end of the crankshaft, causing the cams to go out of time.

If you are planning a large power increase with bigger turbos, GMP Performacne offers an upgraded crank hub package designed for a high-performance engine to handle very high outputs by pinning the cam sprocket to the crankshaft.