We never used these on our championship winning class B bike and our bike was pulling around 52 RWHP after we fitted the Micron exhaust system.  It had a dynojet 2 jet fitted and K&N Filter together with the super-smooth exhaust system, thats it. It was quite a loose motor too!
  Built totally in the spirit of Class B, we brought a road bike of Skids, removed the lights, fitted a fairing and better suspension / brakes and tweeked the motor as above.  Then thrashed the wheels off it 
 
  Andy