My yard squirrel gun shoots 9 to 10 fpe depending upon pellet. It always passes through the head at your distances. I would think an 11 fpe gun acceptable for well-placed headshots on a skunk or possum. Raccoons (at least here) are a little bigger and I would go up a few fpe if I was going to pop one.My .22 LGU was last chrony'd at 11 fpe with a 14.3 gr Crosman Premier. That was right around the 100 shot count and not fully broken in. I passed 500 shots yesterday and plan to shoot across the chrony again. I am resigned to not getting the advertised 12 fpe based on most people talking about 11 fpe results. I too am interested in aftermarket tunes/kits but don't know of any. I think right now the only US option is a lube tune to clean it up, and maybe transfer port work.I was reading last night that many our UK brothers feel opening up the transfer port makes the gun shoot sweeter. I would like to know if there is any incremental increase in velocity but didn't see any quantitative performance change listed, just qualitative references to it shooting smoother. I am wondering if the transfer report improvement might balance out a slight increase in power via spring/washer work?