4 cycle backfiring
the best power would be the minimal amount of castor, running the rest nitromethane. that won't happen. basically, what they are saying is that that's the highest amount of nitro the engine can handle. it will also wear out your engine a bit faster. if you MUST stay at 30% nitro, bakc down to a cooler plug and see if that helps. BUT i would reccomend that you go to around 15%- 20% (i run 20 percent) and use the os #F plug. people are really satisfied with this plug. i know a guy who has had one in his engine for 10 years, and it still tunes really well. the only problem is it is a fairly expensive unit