I was all set to make this mod to my '07 DR-Z400SM. I had the wire; crimps; tools laid out; bodywork off.
But first let's do a quick voltage check at the battery so we can have a before-and-after comparison.
I broke out my Fluke 189, fired up the SM and left the choke on for a fast idle, applied the probes to the battery terminals and read . . . 14.1 VDC!
Maybe at a slow idle. Shut off the choke and it's bumping over at normal idle speed. Check the voltage . . . 14.2 VDC.
Put away the tools, button 'er up and forget about it.
Did Suzuki change anything for the '07? Who knows. The stock wire appears to be 16-18 gauge. Or maybe mine still has good connections throughout. It's not worth cutting into the stock system for 0.2-0.3V.
One other thing:
For those who do this mod, I would recommend splicing to the regulator side of the main fuse. (So it is still charging through the fuse.) Going directly from the voltage regulator to the battery terminal means the battery positive has an unprotected path to ground should the wire you insert ever chafe through. That would be bad (as in fire).