I am not sure if this is a missfire, hitting rev limiter, or trans problem or possibly something else.
But, if i do a holeshot and spin all the way through 1st, it will generally always rev up then it will hop down a few hundred rpms and then go back up before switching gears.

I was thinking it is some tupe of tranmission slippage or somehting but it seems like it could also be misfiring from the optispark or something.

I have an open cutout, it makes a strange noise when it does it.
If this clears it up:

veeeeeeeeeeeeeeeeerrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr rrrrrr vavavava veeeeeeeeeeeeeaaaaaaaaaaaaarrrrrrrrrrrrrrrrrrrrrrr rrrrrrrrrrrrrrrrrrrrr

 

Could possibly be hitting the rev limiter. I had it happen to me one time at the track when I spun the whole way out of first.