I've got a 4" strait exhaust, w/ a 6" or 8" "bell" tip on it. At 2200 RPM's it's got this ungodly loud resonating moan that will give you a migrane after 600 miles! Last night, I shut it off at the motel, and I could still hear it ringing in my ears!! I don't want to lose all the sound, but I've got to get rid of that moan!
Would getting rid of that tip help any, or do I need a muffler?

 

You might try losing the tip and try it. I found putting what they call a resonator on it kills some of the moan but still leaves a nice sound. I did it with my stacks and it sounds real good. They are avalible at big truck dealers I know. A lot of Pete's run these things.

 

I have a flow through muffler on my 4", great sound, wouldn't trade it for a straight pipe any day!!!

 

Put a muffler on it.

 

A resonator will help and some form of Dynamat in the Cab mainly in the rear portion of the cab.

 

Here is a recent thread that has some good info. My links to TDR on this thread have a lot of good info. Not really exhaust related though.

https://www.dieseltruckresource.com/...d.php?t=145066

 

I got a 4" in 4" out commercial truck muffler from the local autoparts store for $60 and it works good. Still have the big rig sound but not the drone in the cab.

 

If its too loud, you're too old! Hahaha. Just kidding.