I'd set it where the car runs decently and doesnt stall or surge, and where you have decent alternator output with a full load of accessories turned on.
It's nice to be at the point where you're making these little decisions, huh bud.
Get the a9l and have it idle at 300rpm. That'll really bring the cam out, or the car will just die. lol
But seriously, if you can leave it right around 800rpm, it would be perfect, if you go 900, you really won't be able to hear the cam but it'll charge a lil better, but if you leave it at 800, you'll hear the cam more and since you won't be at idle for too long(stop signs, lights) it'll still charge when you start moving.
I'd set it where the car runs decently and doesnt stall or surge, and where you have decent alternator output with a full load of accessories turned on.
It's nice to be at the point where you're making these little decisions, huh bud.