I just replaced the OEM muffler on my '91 with the DTM tip style and I have to say that it's a lot louder than I thought it was going to be. It has an intense low booming sound in the cabin at around 2K RPM and I set off a car alarm just backing out of my driveway .. but I was pleasantly surprised that it doesn't appear to be much louder than stock cruising at 65 MPH (I do a lot of highway driving). At idle it has a nice rich sound to it in the open although parked in an open garage, it really gets loud. I had my son drive the car going away from me on our street and it almost seems like it's louder inside the car than outside... at least in the 1000-2500 range. Then it seems quieter inside but raspier outside. Remember that I have the DTM tips that exit the muffler as 3" pipe that then become 2 x 3" tips so there may be more of a megaphone effect than on the single tips.
However, I was not at all pleased with the engineering of the product. The bag of bolts/nuts that it came with to connect to the cats was 8 mm not the 10 mm that is on the cats .. and the cat bolts aren't easily removable anyway. The intake pipes were tack welded to the muffler in what I assume was supposed to be the correct alignment but I had to file the passenger side weld off so I could rotate the intake pipe enough to get the OEM rubber hanger onto the muffler mount (and then rotate it back again). They provided new gaskets but the shape interfered with the heat shield on the cat which also surrounds the mounting flange area. And as the final straw (although this is not an engineering issue), although this was new unit from B&B and in spite of a packing label that was signed as having been checked, the clamps to hold the tips on to the muffler were missing.
I'm also not crazy about the clearance with the rear fascia. Although the tips can be easily adjusted sideways to allow centering in the fascia, and to some degree they can be rotated to get that upswept look, the clearance as they pass under the fascia is so tight that I'm forced to let them hang down more than I think they should be. I think a simple solution to this would be to just raise the mounting points on the muffler about 0.5 inch which would have lowered it creating more clearance with the fascia and allowing the tips to be more upswept.
YMMV