Unsolicited advice
There are spots on the TTi stuff that they acknowledge should be welded, but they give you clamps to hold it together until you get to the muffler shop.
I always have those multi piece sections welded together anyway.
I wouldn't put anything on my car that wasn't mandrel bent. Even the OEMs are finally starting to figure that one out.
redfastback: How much of the time was spent getting the headers to line up with the rest of the exhaust? That was a serious PITA on mine, and then the X-pipe was too wide to match up to the adapters. I ended up ratchet strapping the front "legs" of the X to get it narrow enough.