They sound terrible without baffles. Loud but suck back on decel bad.

 

Try the Big City Thunder baffles. A lot of people ran them on the 3.5's and loved the sound.

 

Eastern Performance makes some nice chrome slash tips for either 3.5 or 4". Also look at Yaffe, he has adapters for his tips or any other Supertrapp tip avail.

 

You can get all kinds of end caps for them from the factory and other places. I run the Rinehart Extreme True Duals 4 inchers (headers and mufflers) with Ness Big Sucker. I think they are plenty loud. Any louder I couldn't hear my stereo! They sound good and the 103 tuned up and dyno'ed out great with S&S 510 cams.

Had 3.5's on my old RK and have been happy with both.