What makes you think Tower cares whether you have success with your engine or not, in fact, if you send your DLE engine to Hobby Services with NGK spark plugs in it, it will be returned to you with the OEM plugs installed. They love to sell ARFs and the engine warranty does not cover your crashed plane if that were to happen, they'd be happy to send you a free OEM plug with your new ARF. Hey!!!...Super Saver Club.....Woo-Hoo!!