I just got back from Silver Lake sand dunes. Before the trip I replaced the factory intake with an Fci, retuned, and installed new spark plug. I did a lot of drag racing, pretty much all day yesterday. After getting home a few hours ago, I removed the spark plug, and cut the threads off to get a better view of what's going on with my tune. I think it looks pretty good, if anything a touch rich, which I'd prefer over lean. Looks a little strange as half of the plug looks really good, the other half shows more of a rich tune. I thought it ran great, seemed to have really strong power everywhere these machines normally do, didn't bog at all and didn't get any backfiring. The closest races I had were against a stock Raptor 700, a modded Polaris Outlaw 525, and a Yfz450, that was supposedly stock, but was much faster than the other 2 Yfz450's I ran against. Here's some pics of the plug I just pulled out.