My fellow modeler has a MVVS 35cc with the new lite ingition on a profile 3D plane. He has the MVVS tuned pipe with the MTW header to reduce weight. The engine has about 2 gallons of 30 to 1 gas through it and we had started trying to get the carb adjusted per Pe's directions. We are getting a very good idle and high end but the mid range is 4 stroking from just under the high end on down to idle. Almost sloppy 4 stroke sound. When we try to lean the low end needle and readjust the high end needle per Pe's instructions to correct the 4 stroking we loose the good transition from low to high. Is the tuned pipe causing this problem? What are we doing wrong?