http://www.ultimatemetal.com/forum/...ut-bridge-vs-emg81-round-2-dtb-content-d.html
I used to really be into the 81 at 18v, but I've kinda gotten tired of it since the diminished focus in the upper mids (and increased woofiness) makes it a bit more of a pain in the ass to seat in a full mix - it does get rid of the sterile quality of the pickup though, but I'd rather use either an 81TW or I guess 89 instead (never liked the 85 except in the brightest of guitars)
EDIT: To be clear, though, my only experience with the 81 @ 18v is in my mahogany Ibanez Prestige, might be different in another