I've run the ProXS previously...on my Supra. I last week I pulled Type-S off my 95. Many eons ago, had a set of XS's on a 4.6.
None of this is really helpful, as it's not the combo you're asking for. If I didn't have a set of Performer RPM mufflers waiting to go on, there is a good chance i would have gone back to the XS in an offset/offset config.
Obviously header/mid-pipe combo will impact the sound a lot. I thought the Borla s-type sounded like poop w/ a BBK Xpipe, and were much better w/ a Prochamber or an H-pipe. The S-types are 5" diam and 10" long c-c cans, so they shouldn't sound at all like the XS.
If I was going to make an assumption, I bet the would be similar to and a little louder than Magnaflows. Very similar internal design, but the XS has less case volume and thinner case material (the magnaflows are ungodly dense), so it will resonate differently.