I was just getting ready to start my enigine when the Service Bulletin from Sonex came out saying that the wrist pin clips(Circlips) that they sent out with the Nikasil cylinder upgrade were not the proper size and could come out. I obtained the cilps from BUGPACK (their item # 4590-10) and then removed the heads and cylinders. Removed the 8 incorrect clips and installed the new clips which were .045 to .050 Inch larger than the ones I took out. The cl;ips were installed with the sharp edge of the clip facing outboard or away from the wrist pin These measurements were taken with the clips in the relaxed state. Really did not enjoy doing this job as I felt I had done a decent job with the original engine assembly. One less thing to worry about now.