I've been experimenting on my Hustler Z with a 23 Kawasaki. The engine came with NGK spark plugs installed and after 200 hours I changed them. I installed a set of Autolite plugs and gapped them at .035 (manual says to set them at .030). Since installing the Autolites and increasing the gap a little the fuel consumption has dropped slightly. With the NGK's gapped at .030 fuel consumption was about 1.7 gallons per hour. With the Autolites set at .035 fuel use has dropped to 1.5 gallons per hour. The engine seems to have more zip and it starts easier. It's only been 45 hours since the change but it looks like this little trick will save some fuel. I know this a post that only gear heads would be interested in, but with the price of gas being what it is, some of you guys might want to try it out for yourself and see if it works for you.