XRAY - Model racing cars

Hi there, maybe someone of yu guys can give me a hand?

My S3102 (Futaba) was little slow on 4.8 volt, can this be helped with a Cap? if so, how will i mount i? .

I just dismounted this servo and put in the Blue Bird BMS-375DMG, 1.6kg way faster 0.13 on 4.8 and will be down on .11 @ 6v 2.3kg..but here again i only have 4.8 in my M18 Pro..any ideas?

a pic on the little servo in my car... (down to 381gr rtr with body and cells)

I believe caps don't increase your voltage average, they just help keep the power more consistent under sudden high drains.

You need to run on 4 cells ?

An option is to get a smaller 5th cell remove the red wire from the servowire from the ESC and power the receiver directly from the 5 cells while the engine still runs on 4 cells.
Or create a small +/- 400 mAh 2 cell LiPo pack and power your receiver with it

Other option is to search for a faster servo, I believe KO has one.

And last option is using a larger servo arm which will create a faster movement.