Back when people had more money to spend on the Hobby OS was the number one selling engine, today people dont want to spend much on certain things. I see people buying 2000 dollar planes then complain about a 25 dollar switch when there is a 15 dollar one. IMO novarossi are good but all are heavy for their size. I like all engines but they all have a weak point. ASP has some really great piston and sleeves yet have weak crankpins. I think most OS clones ASP has the parts will swap over but if you can buy a whole ASP 46 for 50 dollars I would just swap out the crank if the same and have a good engine