Not sure about high volume. I have what I call "tall feet." Somewhat narrow forefoot and heel, but astronomically high instep and arch made even higher with orthotics (gotta get me some cycling specific orthotics). I take out the insole and extend the buckle strap to it's max. Only shoe (with the Genius)I've ever found that fits my instep properly. The previous model without the adjustable instep strap doesn't extend far enough -- just like the other bagillion shoes of the same generation. I won't admit to how many pairs of Genius/Dom 4/5s I own.

Imelda