I've been using the Bosch Platinum+2 spark plugs for years with no problems. They didn't make a dramatic performance increase, actually I couldn't tell any difference between them and regular plugs. But I like that I don't have to gap them and the idea of how they work and make a stronger spark makes sense to me. Kind of going along those same lines, a doctor once told me that basically all diet plans are the same, so if I want to eat chocolate cake then pick one that lets me, but if I want to quit drinking coffee then pick one that doesn't let me do that. Performance tune ups on cars are kind of the same I think, there are some that really do make a big difference, but on other stuff isn't usually worth the money. Like a cap and rotor and spark plug wires, there is the economy priced stuff, then there is the really really expensive stuff, but the performance gains are minimal.
One thing I do swear by though is oil additive. I can't remember what brand I get, but it comes in a small silver colored bottle. With it I notice that my engine temps stay a little lower and oil pressure stays right in the middle at idle, so thats something I always spend the extra couple bucks on each time I change my oil.
