I have found the Roar Legal Picco to be very easy to tune and set up at the track for the conditions. I am racing one now, and my son has one in his car also. You can keep up with the faster cars on a short to medium track. You have to get on the power early, and if you miss a beat the OS TZ's and the like will overtake you.
The JL Red Dot from what I have read is very fast and competitive with the fastest performance engines at the track. Like Roniel_R stated, if you can afford the extra cost purchase one.
For carb set up/tuning just keep it on the rich side and you'll be ok.
"Yellow Jacket" Mugen MTX-6, Picco Torque
TeamNITRO RC Club, Lynwood, Illinois