I'd like to get an X-pipe that fits/tucks in nicely. Ease of installation would probably be the multi-peice kits. So many brands out there! Which one are you running? I'm more interested in trying out the Pypes & UPR X-pipes.
on my gt i had the slp x pipe w/ high flow cats. great midpipe and has attachments that u can remove if u ever buy slp longtubes down the road. didnt tuck the best though, that was also because of the cats though.
i had a bassani x pipe on my car and it fit great, best mid pipe i've ever owned. i didn't like how it sounded and it had cats or i would have kept it. fit was great, i have a mac h pipe now and of course it fits like ass.
I have the Dr. Gas X pipe, fits nice and sounds out of this world. I freaking love it. It is a bit pricey but I think it is well worth it. A couple of pieces have to welded together but man does it sound great.