I think you will have to go a little higher than 20K... 30-50K will help a little more... 50K in my truck still allowed most of the initial torque to be transferred
to the front, therefore leading to quite a bit a of front ballooning... Glad to see you're having a lot of fun with the truck...
I was able to run it the other using the 1520 on 6S. It was a rocket!!!! The 1520 is a torque motor. It barely got warm considering I geared it 44/21 for about 85 mph top speed. There's just not enough space to get it up to speed. I wasn't even halfway on the throttle.
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)