The Nova Rossi stuff is easy to tune and lasts. I've used them for over 15 years. I have a P5 that is 5-6 years old that I'm going to rebuild. The N21R is a great little engine. A Nova Rossi N21R with a Dynamite 86 pipe set should be money. Maybe the 53 depending on what you do with the engine. Break-in, clean filter, everything sealed up (zipties +) and tuning properly makes a big difference on engine life.