Simon (my Golden Retriever) and I camped out at Ocotillo Wells this weekend. Since I suspected that the #162 main jet I had settled on last time out was a little rich, I bought some new plugs and proceeded to do a plug chop with a #160 main. When they say plug chop, the emphasis is on the chop. What you do is cut the body of the plug away so that you can see the color band deposited at the base of the porcelain after a WOT blast. What you're looking for is an approximately 2mm wide band of light brown color. As you can see at the right, that's about what I got with the #160 main (ignore the silver stripe, that's from the hacksaw rubbing on the porcelain). The quad definitely ran better with the slightly leaner jetting; I was able to pull 4th gear up blow sand hill, where previously it'd bog down.