INSTALLED!
Well I rec'd my MRT/JBA catted H pipe today

nice! I had the local muffler shop install it on my 02 (which already had a Amer Thunder CB), since I really don't have time and didn't want to spend my day or night (or both) crawling around underneath my car, wrestling with this pipe.
They had no problem installing it, though the two sections that come together to make up the H were supposed to seal themselves (without the need for a clamp), we opted to weld it as it wasn't completely sealing. The installer also welded up a 1" gap on the front of my pass side flowmaster

(nice job Idlewild Racing! ). The whole setup fits perfectly, just like the OEM pipe - nowhere near interfering or rattling against anything. It really looks like it belongs there - like it should have been there from the factory.
There really is quite a difference between 2.25" and 2.5" pipes - a 1/4" doesn't sound like much, but seeing them side by side, the difference is easily noticable.
It revs more freely now and is pretty loud when running it up to 5K+ to shift, but mellow below that...not much different that with the OEM H pipe. It seems to pull better thoughout the RPM range, but not a huge SOTP's feel - it just feels like it's breathing better.
I was really surprised (and, sadly, somewhat disappointed) with the sound however. Oh, it's a great sound, nice tone - deeper, throatier, muscular - it's sweet, not ratty, no mistaking it's an All American V-8 baby!, but I honestly thought it'd be LOUDER!

My wife's 01, with Flowmasters welded in and a custom sort of catted H, is much louder.
Is this possibly a case of mine being delta flows (which, I believe are what the American Thunder Catback comes with) vs. her weldins, which, I'm not sure, but I think might be the original 40s? Any thoughts? Is it worth switching them out for original 40s?