If things are running good I would tune the carb on the track for the low-end and go for good response and power.
Another way to test things is to squeeze the fuel line , the motor should rev up slightly and die after 5 seconds.
If it revs up immediatly and dies its too lean. If it takes awhile to rev up, its too rich.
You should do this after running the car some. So the car isnt sitting there loading up on fuel. This will make the car seem rich...when it isnt.
Clear the throttle out some times while doing this with some full throttle blips of the throttle.
Also here is an article to help you.
http://rcnitro.com/rn/articles/ht_tunengine_01.asp
Hope this helps , happy tuning.
