How do you like the Diablo tuner? I had one for my old SRT-4 and the power increase was great. I'm considering one for my '03 4.7 as well. I know it can adjust the speedometer for taller tires, but do you know if it will adjust the speedo for shorter tires? I'm going down to 27" tires for my lowering kit and I'd like to keep the gauges accurate.