From what it sounds like no, you don't need them but, don't quote me on that... It's just an inference....:rolleyes:

I just installed the xspeed with the 10T on my RWD car that has bearings and lightweight driveshaft and it goes 30 km/h with fully charged I-C3's. Without load (only on front rollers on speed checker) it goes 31 km/h, which means it gets to speed really quicky. St2 RS motors go about 2km/h on to rollers compared to loaded on all 4 rear rollers.

BTW, you need to connect positve to negative (red to black).

it goes how many km/h :confused:

Sorry about that...edited...30 km/h, 31 km/h w/o a load.

how many I-C3's were you using 4 or 6

...only 4