You should definitely without a doubt reinforce the tranns!!! The stock trans is about good for around 360hp in these trucks before people notice problems on a stock tranny setup!! Shift kit and servos will help..I'd say go FLT honestly..I have a L5 80e and its the best investment i made on this thing so far. It handles the power like its nothing and it shifts into gear without any hesitation!!! The 60e wont be quite as hardcore but will definitely hold some power. I think the 60e fully built will hold around 550 before it lets completely go. If you plan on going further than that then id consider a stock 80e which will handle the same as a fully built 60e