I would do a lipo upgrade to the electric system to support the better servos as a lot of the better servos are more power hungry for obvious reasons. It's gunna be preference more than anything along with how much you wanna spend. Lucky for you the servo that the rtr comes with seem to be a very standard size for 1/10th -1/8th scale applications so the choices abound. You could use the 0231mg from savox for the standard cheaper metal gear servo (waterproof) or the hitec or futaba equivalent. Keep in mind that the gas/break servo doesn't need to have nearly the torque that the steering one does to work properly. I don't know how heavy the steering system is on that truck but if it is heavy then getting something with more torque will keep you from burning them up like the savox 1210-sg. If it was me i might just keep the original gas and break servo stock until it dies and replace it with the stock steering one, when the second one dies then move the one that has been the steering servo to the gas/break position and get a new servo for the steering. Steering servo usually wear out the fastest so if you get quality stuff the timeline should work out in your favor. (keep in mind that i'm just using savox as an example, this doesn't mean that they are the best, they are just what i'm more familiar with)