yep. actually still have it (the y-pipe, that is). the rusted bolts on the rear manifold flange were kinda the last straw of the little problems i had w/ my SVT...well, not really, but it sure didn't help.
regardless - the RT y-pipe/cat is a very well-made affair. very high-quality....i've never seen the SHOshop assy. in person, but i'd venture to guess the RT setup is put together better and perhaps even better designed. again, that's an opinion, and not even a very well-informed one at that, but....there ya go.
i got a really good deal on mine from RT, which is why i got it when i did.
i was already thinking about getting rid of my SVT but decided that even if i bought the y-pipe and sold the car i could always pass the deal along to another CEG'er. which i'm doing - another SE-CEG'er (wes) is supposed to be buying it from me in a week or so.
can't offer any performance #'s, but i'd venture to say they'd at least match, if not improve on, the SHOshop pipe. which is to say, you'd probably notice significant gains w/ it.
hth...
