Mark the U2 and U4 are 6% O2. The steps you have made are in the right direction. Maybe 1 size larger on the main to be safe and then check your plugs fuel ring after a WFO throttle chop. Your pilot setting if correct will be determined by your air screw setting, 1.5 out being the optimum setting. Below 1 out use a richer pilot, past 2.5 lean it out 1 size. This fuel jets in real easily and makes power when done correctly, it also has a super throttle response! Expect a 1-2 hp gain mainly on the top end. :cool: