My vote was for the WS7II mine currently has 8 gallons through it and it still can't be turned over by hand. Some poeple say it lacks on the bottom end grunt but I have not had a single problem clearing any set of jumps with a short run up. I can do it the same as every other car on the track. Where this engine shines is on the top end.... It's awesome to watch it reel in another car down a long straight. I have recently switched the WS7II into my Revo and started running a C5BB in my buggy... This thing is almost too much power to be honest... I had to order a 7mm venturi just to keep the power manageable.