Try out Merlin Glow Plugs. http://www.merlinglowplugs.com/Aircraft.html
His prices are excellent and he gives free shipping over $25 order. He has a chart showing glow plug heat range equivalent and you will probably find his 2003 plug is a good hot plug for most sport flying. Iuse them almost exclusively (unless Ineed a throw away plug for a break in then Igrab whatever is laying around).
He even has a really hot 4 stroke plug 2010 that can sort out problem four stroke engines that want to load up at idle.