You're not going to make an R motor sound "good". Even with a cam they are always buzzy and raspy and high-pitched. The muffler isn't the problem.
You answered a question that wasn't asked. He's looking for a deep sounding exhaust note and the deepest I've heard on an r series is hands down a welded MagnaFlow.
I'd say thats a matter of opinion. They will never sounds like a rumbly V8 or a high strung ferrari but I think you can make just about any engine sound good. I don't think my truck is buzzy or raspy at all and I like the way it sounds, its just a little too loud. I have just a cheap summit racing magnaflow knock off on there. I had a flowmaster and it should like crap and was very buzzy, especially when one of the baffles came loose.
I can second the Borla in general for quality and sound, but my experience is with one on a v-8 and not a 4. The only 4-banger I've played with mufflers on was a 1.9 in a Ford Escort years ago. (mis-spent youth, both literally and financially) The straight pipe on it was LOUD, sounded like a pack of angry hornets, drony and headache inducing on long drives... But it did sound really cool with the pops and rumbles on downshifting. I switched to a glasspack which toned the noise down and made it livable on long drives. The sound went from a pack of angry hornets to one slightly perturbed bumble bee and kept the pop and rumble on the downshifts, so I was happy. If you want to test out different mufflers, I would recommend doing what I did, which is welding an exhaust flange onto the tailpipe. then if you want to test a muffler, you just weld a flange onto the new muffler and bolt it right on.
Definitely a matter of opinion. My built 22r (big cam, majorly ported, big valves, 10.5:1, hei distributor) sounded real good with a magnaflow and 2 1/4" exhaust.. deep lope idle (for a 4 banger) and got real loud but not raspy or anything like a honda..
To get an exhaust note I am happy with I installed a resonator on either side of the muffler. When I had a factory exhaust manifold one resonator was perfect but my Doug Thorley header made my truck sound like a raspy Honda.
If you are looking for a muffler that produces a rich, throaty sound, I suggest that you go for Flowmaster exhaust.
