OK. I went for an unconventional solution and shortened two Champion D21 plugs. They are a very “soft” plug so ran lovely and clean in our Flyer for several hundred miles without a hitch. Thus, they should be ideal for the Super. I don’t see why shortening them would impact their performance but it is going to be easy enough to find out. Anyone else done this? If not, I wonder if its worth adding the details in Yowl.