25 years ago or so I was building 318-2bbl motors for a local oval track series.

I generally prefer to use NGK plugs, and the normal plug for those was a BPR6ES.

I don't remember why I tried them, but the BPR6ET is the same plug with three ground straps and the electrode in the center of them.
No big gains, but they seemed to consistently add a number or two over the std plugs.
They were basically the same price...... So we stuck with them.