There can be serious problems by making the clutch and brake pedals wider than they are. If the extra brake pedal width is toward the accel. side, you could get your foot stuck under the brake pedal during a panic stop. Reason?, your not used to the brake pedal being that far over. Under these circumstances, you might wreck the car and yourself.
If the extra brake pedal width is toward the clutch side, you might accidentally hit the brake when you go to shift. The results aren't as bad, but would be annoying none the less.
You also have to figure in foot size. I'm a 12-13 and have gotten pretty good at "heel-toeing" by pressing the left side of the ball of my foot on the brake and then bending the right side ball downward to blip the gas. So I don't actually use my heel. I can't use the conventional method because my foot is too big to pivot around down there. I just needed to bend the gas pedal about 1/4-3/8" closer to the brake pedal.
So depending on your foot size, you will have to experiment to see what works. Also, when you bring them closer, there is the very real problem of hitting the gas under heavy braking. When the gas pedal is accidentally pressed, it will feel like the brakes have gone out on you. Pretty scary. So don't move them too close together nor raise it much in relation to the brake pedal.
Just use caution and don't move them around or widen them too much as that can lead to serious problems. Start small and always try the mods in an open place or in the driveway first just to make sure there are no problems.
Another thread on the topic.
http://www.ls1.com/forums/showthread.php?t=488368Also check this video about 45 seconds in for an example of the style I use.
http://www.pfyc.com/z06/virfull0303.wmvHere is the guys site. Some other good videos are here, also.