Well I have 2 Novarossi's a turbo 421 and a normal 421 , the turbo engine has more rip mid to top and is VERY picky to needle and ambient temps where as the normal 421 is a mild manored powerhouse! Out of the 2 I like both ,the turbo version is great for slippery tracks and both run about 7.5 - 8 minutes runtime tuned safe! I have a non turbo CLB 4N that is about as sycho as it gets power and smoothness wise , and fuel economy is pretty good too .
I have seen a lot of turbo and non-turbo engines run and I think the best turbo plugged engine is an OS and the best non turbo would be a Nova or RB.
