I wouldnt worry much about the smoke out of the exhaust at idle, but under hard acceleration you should see a stream of smoke. Be more concerened about the temps, if its over 275 its too hot and that is a sign of being to lean. If your engine idles for 20 seconds I would say that your low end needle is set a hair to lean, try and make it so that the engine will start to load up after about 8-10 seconds. Ideal engine temps for .12 or .15 engines are 220-250 after some hard laps at full speed. Dont forget that you have to adjust your needles every day to achieve the proper needle settings and desired engine temps. Hang in there youll get it.