I installed this conversion kit in my EB4 S3 without any problems. I had to file down a piece of plastic on the mudguard a little but thats all. Everything you need is included and fits nicely. Even a pinion gear is included, a 12T. The best part is that I didn't have to cut or drill anything so all original parts are intact so in an hour you can change it back no nitro. I just removed the servotray, the holder for the steering servo is durable enough, just use the same screws in the original tray posts.
The only negative part is that the velcro straps in the battery tray are too short, at least for my 4S LiPo. It is easily fixed with new velcro. Remember to use thread lock, I didn't and lost two screws.