Special technique? I dont know,...I just used a cylinder shaped sanding piece and went smoothly along the areas I needed to, to allow my car to be able to run smoothly but at the same time not taking off too much of the body kit that would leave it looking weird. If your doing your g35 (from your sig) I would reconsider doing this because since you cannot change your side fenders, like I can with the lancer, if you put the car rims back on it might look very odd because you will have large wheel areas with small rims. But anyways if you are going to still go with this. Use a dremel kit with a roundish or cylinder shaped sanding piece, go lightly along the areas needed until they are wide enough to give an even look and be very careful not to over sand areas on the inner part of the body( for the turning to be allowed) or else they may become too thin and break. You might also notice that on one side, on the chassis near the front gear box) you may need to sand a little bit to allow the wheel to move freely without any interference(to find this, just turn the wheels with your hands, and see where the tire might be rubbing, again be very careful doing this). Also I dont know if it is just my dremel kit or what but mine has different speeds, for mine a used one of the lowest ones just to be safe. But other than that good luck and hope you enjoy this small mod
bc_edition