have you had the bike on a rolling road ? if its stage 1 tuned it should be making somewhere in the region of 123bhp or more ! . not many companies did tuning for the storm , was it REVOLUTION ? on the receipt ? , if it was roger he would normally do an airbox conversion , has yours got this ? / if any of the above are yes LEAVE THE K&N IN !! , If not then it sounds more like a stage1 k&n kit was fitted , in which case ... leave the filter in , its been set up to run with it , if you take it out it will run like a bag o s*it . IMHO .