RPM AIR-GAP carb spacer?

I can save you a lot of trouble. I ran an air gap on my old 340 that went 11.80's. I also dynoed several spacer's. Go buy an HVH 1" 4 hole tappered and be done with it. I gained a 1/10 on a good tune up with that spacer. I run one of these under my dominator on my 416 now. They are a little spendy but worth it.