Bought some Titanium Valve Spring Retainers for my rebuild. Are these things really worth it though? 260 bucks from FWD, and I might have buyers remorse. The dude at the machine shop who's doing the work on my motor said they aren't really necessary unless you are running an extremely high horsepower car or if it's high revving, like over 9,000rpms. He said he's done alot of work on rebuilds of 500hp cars running standard steel retainers with no problems. Are these just a gimmick or do they actually DO anything? Performance wise, reliability? Anything? Does anyone have proof of the claims?