On the virago xv 535 the exhaust travels into a collector box then out into the baffels. so removed my exhast system as a whole and drilled a quater size hole in the bottom of the collector box. Sounds much better but it wasnt loud enough so i made the hole bigger and found the bigger the hole the louder. bike sounds much better without spending money. I dont know if i should jet the carbs but the spark plugs look fine and runs perfect.