Interesting discussion. Can't speak for the D5 but the STS 3 ports seemed to be " in the middle of the pack" when it comes to power. I am sure the JP will be at least as fast as the D5. D5 will probably last longer than a JP:s (A standard NS12 will last longe rthan an STS though, all other things being equal) But the STS:s I have tried have all lacked in bottom end, They are good value for what you pay, but not the "ultimate" in power. The STS 3-ports was also a little easier to cook than the Nova Rossi based engines I have tried. For workmanship for sure the STS falls behind the Novas. The STS is not in anyway a bad engine, just a little "cheaper" than the Novas. Great engine for club racing though, especially when you consider that you can buy almost 2 STS:s for the price of one Nova....