To modify or not is totally depends on your foot (well heel and toes) agility and flexability... Well it also depends on the kind and size of shoes you wearing too.
I don't have a big foot, my size 10 Lugz is the best shoe with the nsx. (believe it or not!!) I don't recommend that to any driving enthusiasts cuz it against all the "rules" or racing shoes... it goes especially well with the nsx on street driving, the 1 inch tall heel help me blip the throttle more while maintaining light braking.
However, If I go to track, which in the case you foot would planted on the brake pedals more, a proper racing shoes would def. a plus.
My point is that for Street driving, the heel and toe is more for pleasure and piece of mind (rev matching)... I do heel and toe from 5 to 3rd all the time and 3 to 2 and it's totally done in less than 4500 rpm range... If you think about it, you don't do that on track... Thus diff. equipment and timing would be needed.
Thus the adding shims or "clip-on" pedals would helped on the street. (same goes to my wearing higher heels shoes).