Well, I did it also, got "piped" today. It was a chore finding the 3.5" stock, but I ran across a supplier today and snatched up a piece. He also had some FPPF Total Power that I picked up.
I purchased a 3' section of Aluminized for $15. Had the installer flare the ends, cut the OEM muffler out and welded in the piece after a bit of trimming. Labor costs - $30. Total cost..... $45
My impressions -
At idle no discernable difference.. accellerate away at a casual pace and you can notice a lower rumble. Rolled the windows down in traffic, sounds like a deep aftermarket exhaust on a gasser, with the usual diesel inflections.
But... when you romp on it
.. hard to describe, but the phrase vulgar obscene mutant Freightliner comes to mind. It sounds like what I suppose open headers on a Diesel would sound like, "rapped out" as Dieselman84 calls it fits. No regrets, I'd bet performance and EGT reduction-wise it's as good or better than a 4" system. Not for everyone, but I'm quite satisfied.
Mike