DIY First gear or speed output?

[Wdbi]

I have a JB4 with a mhd backend flash and i was wondering if there was an output I can use to trigger a device. I need the device to only be activated in first gear or below a certain speed.

 

[Rob09msport]

Wonder if you could use the speed warning function and pick it up over canbus ?

 

[doublespaces]

With creative use, you could possibly use the exhaust flapper but it would require custom logic in the DME most likely.