I have resonated test pipes and yes they're still raspy. I've had them for well about 15k miles.
As for a significant change in the sound, mine got a lot louder when I put in a Flowmaster muffler.
I'm taking it off and putting stock back on for now and will sell the Flowmaster. Why might you ask? I'm going with dual exhaust when I get twins, and I'll have to use 2 mufflers with the true dual.
I might throw it on eBay when it's off, but like all things of mine for the FX I'll post it up here.
Will soon have resonated test pipes, Flowmaster muffler that uses stock tips and pretty much bolts right up (had them weld in the Flowmaster where the stock muffler was so it used mostly stock piping), and much, much later a set of headers for sale. In a somewhat unrelated topic, I'll also be selling the supercharger as soon as I stop being lazy and remove the fuel pump.