Boy oh boy I did the muffler Mod to my 310 and adjusted the carb. I would say it cuts twice as fast....I do thinning in the nat. forest in missouri around the salem area( if you want to know) I avereged 5/8 an acre per. hour befor but after the mods. I am up to 1 and 1/8 acre per. hour...thanks everyone for the wealth of knoledge here you guys are making me money LOL HEHEHEHE