It looks like from what I've found that regardless of gear once the ecm sees 189mph it kicks in a rev limiter. So have to somehow trick the pcm to see less mph. Can modify the speed pickups but then never have a properly reading speedo
You're treading up a slippery slope here. The speed for the G4 comes off the rear wheel speed sensor. If you screw around with that, without matching it to the front wheel speed sensor, then the traction control/ABS will be affected. So you'll be spending way more time/money figuring out how to create a matching wheel speed sensor or piggyback electronic unit than you will paying for the flash kit and just checking the box in the software.
Aside from that, the "rev limiter" you mention is a combination of fuel, ignition timing, and secondary throttle plates. They all work in conjunction to limit power for TC use and speed restrictions.
I'm not sure what flash kit you had for the Suzuki or what ECU the Suzuki uses. But if it's a Woolich kit and it is for the Mitsubishi ECU type, then you may be OK reusing the kit with a new harness and BIN file to lower the buy-in cost some. That's worth more of an investigation that trying the circumvent the other stuff.