I like the on/off switch especially for my Ford V-10. At 10-12 miles a gallon, premium gets mighty expensive especially when the stock V-10 has plenty of grunt stock. And running a chip increases the fuel and advances the timing. So it's normal that chipped engines have excess carbon build-up in the combustion chamber. To be able to switch back to stock gives you the ability to run cheaper fuel, and also allows your engine to run cleaner and get rid of some of the gunk that builds up in there. Since the Kenne Bell switch chip costs no more than a Superchip, or any other aftermarket chip, why wouldn't you want to have one ? Or you can run a performance program AND a ultra high performance "off-road or race track only" type program for the ultimate power gains since the Kenne Bell chip is basically 2 chips in one. Try it, you'll like it, Ken 1999 SE Contour Zetec, 1998 E-350 XLT V-10.
