Indexing plugs ??

The spark plug gap opening should face the exh valve. Indexing does have definate positive effects. How much depends on how bad they are now really. Yhe guys that showed me just drew a small line on the ceramic in line witht he gap, and then threaded them in the heads to see where they would stop. Then adjust with shims. There is also a benefit to side gapping plugs...But they are not great fro street driving, so I'd do a "track only" set.