P30 7.4 speed limiter question and accessories

[Boost]

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!

[Boost]

Ok so apparently there is a switch to shut everything off in the back that will help a lot I suppose.

[ScarabEpic22]

Might be easier to pull the PCM if you can and bench flash it, if not then try to pull as many of the fuses for the stereo, fridge, etc as you can.

Edit: That switch should help nicely!

[Boost]

Thanks Erik!

[hog]

Is this an L29 7.4 or a L21 7.4 engine? The P30's came with either. The L21 uses CNP and ETC, while the L29 is distributer and cable throttle. L21 will have the 2x 80 pin dual connectos PCM 512kb PCM and Vette O/s while the L29 with have the 4 connector blackbox PCM.

peace
Hog

[Boost]

Thanks for the info. I ended up not doing this one, and not sure which it was. Thanks though!