For you guys with a fixed pitch prop; OK, you've been going to fly-ins or running around with your buddies who have an O-360 vs your O-320. You like the extra performance they've been getting, and have been giving serious thought to upgrading to an O-360 yourself. Let's see, how much is that going to cost? $20k; $40k? Oh yes, and when you do, you're also going to have to put on a different prop. More $! I've mentioned that dreaded RED-LINE before, that strikes fear in the hearts of even the staunchest and strongest among us! But just for kicks and giggles, what if instead of going to the expense of another engine AND a new prop, instead we went out and only got a new prop that would let us turn 12.5% more rpm to give us the same power we would get with the O-360! That means instead of 2700 rpm at WOT in cruise, we would turn up, if you're standing, please sit down for this, 3037.5 rpm! I know, I know! By saying this I've probably put a tear in the space-time continuum that will never be repaired in our lifetime. But, consider this: you will go 4% faster, turn 4% more rpm on takeoff for more acceleration and better high-hot performance, and all of the extra power will translate into a higher climb-rate. And this for just the cost of a new prop. Does it get any better than this? But this isn't for the faint of heart, the traditionalists who won't turn more than 2500 rpm, who want their engine to last much more than their lifetime, for those who know that an aircraft engine, unlike your car's engine that red-lines at 6k or 7k, will blow up the moment you go 1 rpm over that little line. Ok! Save your engine that additional 100 or 200 hours for the next owner, and sweat out that next marginal performance takeoff or seeing your buddies leave you behind. Better safe than sorry, I always say! How about this; call Lycoming and ask them if their engines will blow up if operated beyond the red-line on the tach. Push them for a good answer on this and TBO. 'Bet all you'll get is obfuscation and CYA! You do know that the geared Lycomings operate in excess of 3000 rpm! Ask them about that and why those engines can take it but yours can't. Lycoming states for the GO-480 and GO-435. "In the climb configuration, we recommend full throttle throughout the climb...with RPM reductions initially to 3000 RPM and then 2750 RPM for prolonged climb." (Lycoming Flyer Key Reprints, top, P.43) This IS EXPERIMENTAL aviation!