Hi Lenny,
Similar to you I had a dmch jet-coated exhaust and last winter replaced it with a dpi stainless exhaust as the Houston one had developed a few rust holes at the manifold. The Houston one was much louder but I'm much happier with the dpi volume. Less drone at speed but you lose the nice rumble at low speed.
Metal looks thicker than the original Houston exhaust, I haven't seen the Houston stainless system.
Didn't notice any real difference in performance.
However don't expect quick responses from dpi, I first emailed a month ago with 2 more emails looking to order high value parts and haven't had any reply.