Before you toss the motor, try this setup
http://viper-rc.com/forums/index.php...91.0;attach=63.
It makes a fairly smooth transition from boost to top speed timing. If you're still getting lag then you may have an issue with the motor. I've shown a couple of my VST's 200+ degrees (my bad), they're still running well, just replaced the rotors. Let me know how it works out.