My 97 accord has been making this grinding noise when I start accelerating past 20mphs. It’ll go away once I got over 3,000 rpm’s but the moment it shifts the grinding noise comes back until I let off the gas, then it goes away again. What seems to be the issue? The person I bought it off of said it’s the muffler but I think that’s a straight up lie. Help please, thank you!

 

Check the muffler hangers, but can also check your engine mounts.

A good way to check mounts is to have someone look at the engine while you rev it while pressing the brakes, you will see if something is vibrating there etc.