I have a 2005 GW208 with Yamaha F150 that just suffered a catastrophic failure. Severe corrosion in manifold and engine block. This motor had been flushed after each use. The failure occurred with1340 hours on the engine. I had 15 seasons of excellent performance until this issue occurred. I am not sure how prevalent the issue is - but I am incredibly disappointed. I just wanted to let the community know. Engine had been running well and suddenly died. Motor ran perfectly with cowl off, and would not run at all with cowl on. The exhaust fumes choked its ability to breathe. It appears to me that the protective coating on the gas path surfaces failed.