I don't see the need of the 1521, I think the 1515 will suffice. I got a 2.5d/1515 (1700kv and on 5s its freakishly strong, I'm hoping to try it on 6s with a MMM soon. Don't got the money right now, but soon
Work because i gotta, play because i wanna
People here hate Nitro, I love it. I start it, run it about 50 ft from me and it dies, I go after it. Perfect exercise
Dont forget theres more than just how fast the motor is turning..... with the 1515/1y with 6s setup you will have increased stress on your drivetrain, escpecially the diffs, and getting that power to be usable...wheelies will get old fast, you can gear up to help with that, I have put some extra weight in the nose to help with wheelies,