Try the TM springs and then purple front and the pinkish at the rear for indoor.
Lots of tracktion and no roll if you use the front swaybar(no rear swaybar).
I use Tamiya 400 oil in the shocks front and rear with standard pistons in the shocks,epa steering at 65% and sorex 28 front and sorex 24 at the rear.
If you can use it prepair your tire with tracktion fluid on the rear complete and at the front just the inside part of the tire and i also use tire warmers when permitted.
Camber rear at 3 degrees and front at 1.5 degrees.
Rear turnbuckles on the inside position on the hubs and 2 spacer rings on the bulkhead side to get them horizontal.
Shocks rear at them most inside position at the top and front on the outside.
Toe in rear at 2.5 and front neutral
This all will get you more grip on the rear.
I also run a 13.5 GM with lipo and it isn't loose.

cheers Roy