As an only truck I would not recomend a 4stroker. They are fun but not the norm and not speed freaks like the 2 strokes. You need to realize the 4stroker is maxxed out at 21,000 rpm's and will have to be running pretty hard to reach that. It will run with some .21's but not the top end ones. They have their own little quirks and sometimes it's best to just walk away and run another truck, hence the reason for my screen name, I almost never leave the track until I want to because if I break I just go get another truck, if one doesn't want to run right that day I just get another. I have done the fourstroke because nobody had even seen or heard one around here and it was a challenge that I wanted to take on. It's all in fun and it's great fun at the track when you leave it on the pit table all afternoon and all the guys are drooling over it, then you fire it up and everybody want's one. You need to come to the track and check it out!
BTW last pm I received from you was 12-26 about the EK-4.