I am going to try to adjust a big stretch limo truck speedo for 22.5 inch wheels and big tires, also slightly bump the speed limiter which is at 68 mph right now. It is a '98 with a 454, I believe a P30. There is a setting in those Vortec PCMs for top speed, right? Also, this thing of course has a ton of stuff like refrigerators, various lights and accessories, it's a limo so what precautions can I / should I take so nothing goes wrong while flashing. Should I try to disable as much stuff as possible and pull fuses, or just try to read and write and see what happens. Thanks in advance for the advice!