I was running the 1515/1y in maxx and on 4s was not impressive 5s was alot better 6s was really sweet...also I may be wrong but with 1515/2y in the rc calulator it showed with 62/26 gearing only 30ish mph on 6s ...maybe I did that wrong...but for me the maxx was heavy and needed alot of umph to move it so I had 5s in her with 2200kv motor....and with my e-revo it was quick on just 4s with 1515/1y