I am eyeballing a boat with what was originally the 375hp version. Owner installed Raylar HO kit with the different cam and ECM. It also had the Exhaust restrictors pulled and the fuel pressure regulator installed.

Engine has 303 hours on it.

Any up and coming issues like valve springs and such? Any other issues to look out for with that engine?

Boat is an 02 so its hours have been spread out, but then again it's in Wisc. and there's only 14 minutes of summer anyways.

Well our stock 496 had almost 900 hours between mid '05 and early '09 without a hiccup (with the motor). Tests still showed plenty of power and that it wasn't due for a refresh. This was in saltwater.

With that said, I don't know how much more wear and tear the kit adds.

I am aware of one that broke a valve spring after 304 hours on the engine and ~220hr of that with the kit.

IM sure it al depends on how hard you run the motor and how long you stay at wide open throtle for .
i know of some cruiser boat's with almost 2000 hour's but they just cruise and dont run the motor's hard at all .
all i can say is the longer the motor stay's at higher rpms the shorter the life is going to be on any motor .

miike