Big buzzing from the exhaust

Hello friends my vehicle is 307 cc. Exhaust sound is above the level that should be in my car. He said no exhausting trouble. What is the reason for a huge hum at 3000 rpm at 50th and 70th km / h in 3rd gear?

I had the last muffler checked, bro. And wedges. He usually does such things from the last muffler.

I didn't get it checked but thank you.

then have the exhaust chocks and a check on the manifold. wedges may look solid but may be touching the vehicle as it loses its feature in bends.