I've seen a high idle pin on my BHW wiring diagrams, but I'm not sure if that's just for high idle for warm up (around 1200rpm), or something faster. I've got an increased cold idle tune with my Malone tune, but once the coolant temp comes up, it's back down to 850-900. I'm also interested in getting a high idle setting for winching.
The biggest reason for higher rpms is cooling, from what I understand. Running alternators at lower speeds isnt good long term due to heat, the faster speeds means more air movement and better cooling, at least for the air cooled versions. I know there is a liquid cooled alternator that is 200A(?) that is available on a few touareg and maybe a Phaeton or W12 motors. I'd love to have one of those, but its pretty far down on the upgrade list.
Maybe I'm a dummy with alternators, but I understood that they also need a certain rpm to be excited and start charging or putting out charge. Which is why a dead battery wont effectively recharge at idle, but needs higher rpms and a load from driving.
I'm happy to get educated though! And I still want a high idle option, not a wedge or plunger system that is weirdly rigged.