I used the words pop and snap which may not be the best choice of words to describe what I'm hearing. My friend little pistion simply describes it as a stumble which it is, he was here when I ran the turbine. With the total spool time beiing 7 to 8 seconds the turbine spends 1/2 of that time accelerating from 50 to 70 k rpm. As it is accelerating it is like the flame in the combustion chamber is encountering turbulance and is being whipped around, like the flame itself is struggling. To me it is a very subdued popping and snapping sound. I feel like 7 to 8 seconds for a test stand spool up in a current generation turbine is unacceptable. The exact words used when describing the spool time of this turbine before I purchased it was "fastest in its class". The 7 to 8 second spool time that I'm experiencing is niether fast nor fastest in its class. Arno the owner of evo when ask what the spool time should be for the booster 90 said 3.4 seconds. Quite honestly I cannot fly and enjoy this turbine with the spool time being so far out of spec. I will try the parameter changes as recommend and hope that takes care of it. If not I'll box it up and send it in. I want to say out right that I'm not flaming Chad or Evo. Chad has been great at returning my phone calls and helping me on both of the Evo turbines I own. It was my preference to not name names at this point but rather educate my self on spool up time as best as possible. The video I took which is not the greatest quality can be found here.

http://www.youtube.com/watch?v=VWd7De_KPjU
Luckyflyer