Ive been running sidegapped plugs for a number of years now but I have never noticed a significant reduction in plug life. In fact, the ones I pulled out of the GP before installing BRISK plugs had about 8k on them and they still looked top notch.
A few things to keep in mind to help with plug life:
1. Be CERTAIN you do not cut the ground electrode beyond the radius of the center electrode. Doing so will shorten the life of the plug because it causes the center electrode to wear at an angle.
2. Be sure to de-burr the ground electrode. Get rid of those sharp edges. They can create hot spots.
3. Reduce your gap by about 5 - 10 thousandths.
I have been told by a few racers to bevel the sides of the ground electrode. Whether that helps or not Im not sure, it would go towards #2 above though so I dont suppose it would hurt.
The biggest single contributor to plug wear in side gapped plugs I have seen is cutting the ground electrode beyond the radius of the center electrode. You dont want it half way over the center electrode, you want it closer to the edge without going beyond it. I have never seen a side gapped plug that was cut half way over the center electrode and Ive seen the drag strip drivers do it, circle track drivers do it, etc and none of them were cut so that only half of the center electrode was exposed.
However, if you prefer to be more on the safe side, that would be a good starting point and then slowly grind the ground electrode back. I personally use my dremel with a cutoff wheel and then I use the round sand paper discs to knock down all the sharp edges, burrs and so forth.
