Plugs and O'donnell Plugs. I have good success running these plugs. They are really durable. With standard head shimming from the MFR below are some comments I have about the O'donnell plugs.

77T - Pretty Hot plug. If your running 16% nitro this is probably the right plug to use or the 97T. I probably wouldn't run this plug with anything over 20% nitro.

97T- Between a Novarossi 6 & 7 plug. These seem a little hotter than a normal 7 plug from Nova, but not quite a 6.

99T - Pretty close to a Nova 7 plug, perhaps a little colder.

These have just been my experiences..... of course others may have different experiences.