12B
Matt;
It's been tested in stock & 19T by championship calibre drivers and AE's Walt Henderson (usual a-main contender) has tested it in mod. So for, they all liked it and felt it was clearly better in stock and 19T and at least as good or better than the older Speed 12 was in mod. The better the traction, or bigger the track = the better it will be in Mod.
Hope it works well for you too.
Dale - PROTOform