Side Gapped plugs...

I tried Splitfire plugs when they first came out in my 5.0 with 100 HP nitrous kit. I did not notice ANY difference in anything (WOT acceleration, MPG, idle stability, etc) between the Splitfires and the stock Motorcraft copper plugs. At the next plug change I went back to the OEM Motorcraft plugs that were 1/3 the price of the Spitfires.

Back in the day I put a 302 in my 65 Falcon with TRW 12-1 pistons and Vic Jr heads. After gapping the plugs the pistons would close the gap due to contact so I cut the electrodes down and side gapped them and was good to go even with a 275 shot.

They actuaally do make plugs already side gapped like this. Autolite sells them as their AR numbered plugs. I'm sure other manufacturers do, but the Autolites I know of, but they are more expensive, just do the yourself and save.

https://www.autolite.com/products/racing...erformance