Well since my Lehner is toast I need to get another motor. I've owned a Neu before and loved it, so I'm going back. My question is about the 1515 vs the 1521. What advantage does the 1521 have over the 1515? I figure if I toasted a Lehner 1940 in a 6 minute race I want to over do it a little so I never have this happen again.