I've got 2 discovery engines bought 6 month apart. Latest was August from Horizon, which should be the newest.. Both tune well and run great. When I started with the first Discovery I had trouble getting a mid range bog out of it. I went to a hotter plug, OD 77T retuned and haven't had that problem since. With the new Disco I knew to go with the hotter plug and haven't had any troubles with it at all..

I'll also say I don't do much for maintenance on nitro engines. Changing plugs as needed, and front bearings, is about all I do. I'm not sure how after run oils might effect plug life/heat ranges over time.. My First disco needs a front bearing now, and has needed for about the last gallon. I have a Avid 7x19x6 ceramic on the way. If some of you are having idle issues or changes in tune as the engine runs then it could very well be front bearing related.. 3-4 gallons on a $10 or cheaper bearing is about as good as you can hope for..