My Son bought his from Jegs and pretty sure he only has one going into a soft plug hole. Later in the year when we run the Halloween races in PA and Ohio he loves them. It saves him a lot of alcohol.

1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time