If that's the case, I'm staying with 6S on my 1515 1Y then. Right now, it's geared 51/20 with 43/13 1/8 scale diffs.
Castle Neu 1520 on 6S LiPo Powered Gmaxx (Nitro Killer)
Predator with OS .21TM
Supermaxx with Mach .26
Revo with OS .18TZ
Kyosho ST-RR Conversion
Ofna CR with Tekin ESC/Motor (2)