A 3800kv will not be a speed demon cant fit a large enough pinion and spur combo for gear speeds.. If you want to go for speed there are a few things your gonna need to know.In a traxxas with stock gear case and axles you will twist the gearcase and blow the axels.. I go with as big a Kv motor as you can.and a Rpm gearcase or another aluminum gearcase with metel motor Mount.I built my speed run rustler. with a old but very good tekin redline non sensored motor a offbrand esc That could be programmed with card to not need a sensore.some steel CVDs good set of hub bearing not bushing and gearcase bearing. and a few changes thru the years in a 2 cell lipo.. from 45c to 100c in the 5000 mah range never charged at more than 1.5C.Id go look for a RX8 with a large kv motor there are some in the 6400kv range,building a speed car means your not gonna have back n forth runs till your battery needs a change its down and back a few hundred feet and return to cool down till next run. thats it.You want speed let me know send me a IM then ill give you some pointers.