Loud noise during a certain window of rpm

[brokenbimmer533]

To start off my car is a 1986 325e with 229000 miles. The noise is most noticeable when driving on the highway. I can hear it in the other gears but its loudest in 5th. The noise starts at ~2750 and ends by ~2900. This puts the noise at 75mph. Noise is loud enough to over power conversation and the stereo at normal volume. The noise only occurs when I'm accelerating or maintaining speed through that rpm range. I think it has to be something with the exhaust but I'm not positive. It definitely sounds like the exhaust gets louder for that 150rpm window.
Any help or more questions is greatly appreciated.

[kronus]

Exhaust heat shields. I have a similar problem due to one of my motor mount arms being poorly attached.

[brokenbimmer533]

Thanks for the reply, Ill check it out next time we get a relatively warm day.

[ozner]

Where would i check for the heat shields?

[e34john]

They are over the muffler. I think I took mine out.