a tip is to keep these parts for a while. try them, test them and see if you like each one any different before yo go selling them. they are all options to fine tune your setup for your track.
Serpent - Walter RC
Serpent E Power ..... Serpent 747 Reds M3T
Serpent 966-TE Reds M7T .... S411ERYX Speedpassion 3.5T, T-Shox
Serpent 811-TE REDs R5T