Known Problems at 150k miles

whats are the known problems at 150k miles. i know one is vaulve guide seals

That would be the main one on my mind. Basically just the stuff in the FAQ. I'd check for smoke of any kind. Make sure the oil cooler isn't leaking. Check all fluid. Check the suspension and shocks. Check to make sure the tuneups had been done. Active aero malfunctions. Boost leaks as with any mileage. Rust. Synchros. Those are what basically come to mind. Why you thinking of buying a third?

if you still have the original turbos on your car, check those for shaft play as well as they can start to wear down pretty quickly at those kinds of mileage, but grant it, i haven't see many other cars with stock turbos that can last that many miles