a buddy of mine cut the muffler off his stock 99 f350 psd. will that hurt it in any way?

 

It might hurt someone's ears standing next to it Really, I've not come accross anyone saying it does so far.... My next exhaust has a muffler, but no kitty

 

no, it won't hurt it, just move some low-end torque up through the power band.
Now, you can hurt an engine running nothing at all, as in,( no exhaust headers or
mufflers). And I'm not sure but, I don't think it's safe it is to run straight headers
or manifolds.

 

I just put a 4" pipe from the turbo back, nothin' but great sound and what seems to be a lot more performance, no kitty, no muffler just a mean soundin' truck that twists heads!

 

Diesels really don't need a lot of back pressure and may help it.
I would highly suggest keeping either the kitty or the muffler as it may be too loud?

 

when you have a turbo, such as on a psd....any backpressure after the turbo is just hindering performance....

 

What he said. The less back pressure on a turbo engine the better.