I heard most LT installs on our cars require lifting the engine off the mounts a couple inches to squeeze em in there, if that's the case I definitely don't have the equipment to do that right now
Mac and Pacesetter are the only ones that make long tubes for the v6.
Mac's do not require lifting the engine, I don't know about the pacesetters.
Both will eventually lose their luster, but Pacesetters rust remarkably quick, and from what I have read, they have fitment issues.
The mac has a slight fitment issue on the passenger side with clearing the k member. We solved this by hammering a small dent into the header itself, and it doesn't seem to have hurt anything. I found out later that we could have used spacers, but then you are opening up a pandoras box of exhaust leak issues.
Whatever you do, order some OEM metal header gaskets. DO NOT USE the paper/carbon gaskets that come with aftermarket headers, not even the ones that are supposed to be the "best" (like percys carbon, in my case).