As stated, an impact is about the only efficient way to break them loose. All it takes is a quick liittle zap and they come loose. Go to a harbor freight or discount tool place and pick up an electric one and you'll have it done in no time, or take your socket and forks to a buddy that has one, or even a local auto repair place and flip them $10 to break them loose if you don't want to buy the impact. Otherwise you'll be messing with those bolts for hours or days before you finally give up.
Also, if you buggered up those bolts by trying to get them out by hand, you might think about replacing them. Alot of guys will replace them, but I re-used mine.
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2015 Denim Black RG, FM ss ceramic coated 2-1-2 pipe, White Bros Original E Series Mufflers, FM ac, PV Tuner