i have my bike with fmf's at +4 stock factory port work.. stock bore.. no detonation.. my duneported bike with 34mm carbs is at +5..it burns 91/100 octane mix.. no detonation.. once again my dads bike with dmc's on it. stock airbox and carbs.. stock stroke and port.. with +4 timing.. no detonation.. it all depends on how well tuned ur bike is also