The PO of my car put an extension on the gas pedal, much like you are talking about. It is simply a metal plate cut to the size of the gas pedal and bolted at all four corners with "bushing" spacers between the pedal and the plate. Having not taken it on the track yet (see
http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=66894 ), I am not sure if the brake fade such as Dean mentioned will be a problem. But for street driving, I heel and toe all the time. It is super easy with the extension on the gas pedal. At least when I am barefoot. Putting on my shoes (size 13), makes it a little more of an issue. I have to be very careful to not stomp on the gas at the same time as the brake due to the close proximity of the pedals. Dean now has me wondering if I will indeed have a problem with it when the brakes begin to fade, and the brake pedal starts to travel farther downward.