My Specialty Spares with modified baffles are very loud. I only have about 1/4 to 1/3 of my fiberglass left in them. They absolutely RIP when I open them up. It's very easy to make them louder or quieter by adding or removing fiberglass (at leas on SS's, can speak for Epco's), but right now they are perfect for me.
Without baffles it's almost unbearable, but amazing to try at least once.
I have heard, however, that in unmodified form both pipes sound very similar - perhaps with a slight edge to the SS's on the loudness level.
Pic of my baffles (wrapped the fiberglass in hardware cloth to hold it together):
