I removed the cat (for testing) and stock muffler. I replaced with two 4"X36" straight through style mufflers to keep it on the quiet side.
Now it seems Ive lost around 100 deg. on the max egts but it dont seem as snappy as with the stock parts.
Am I nuts or has anyone else noticed this?
Also installed an amsoil air filter in a modded stock air box.

Thanks Mooseman

 

when I bought my 01 it was straight piped but it droned on the freeway BAD!!
so I put a 4" hog exhaust on with a their muffler. I swear it was more responsive off the line and sounded way better with the HOG setup!! IMO

but my friend has a 05 without the muffler and I love it, no drone when I rode in it.

 

It probably lost its snappiness because you've created less backpressure which means the turbo isn't spooling up as quickly. Surprised it isn't plenty though with that tuner you've got. The 3rd gens seem to not have that bad of a drone with no muffler especially if you leave the kitty. That sound-

 

I didn't think you wanted back pressure on a diesel.