1 3/4" with .134 wall dom pipe. paid about $500 shipped to my work which saved about $30. installed by me and a buddy using a wire feed mig.
the main hoop comes assembled, the rear bars have to be fitted then welded to the hoop. the hoop and rear bars got welded in then we fitted the front pads and welded. i already had the interior removed and took about 6 hours.
the next time i put a cage in a car i will buy the bolt in, then weld it in. my reasoning behind this is when you buy a bolt in they supply plates for the under side of the car to bolt the interior pads to.
i like the fact that the floor pan is reinforced on the underside by those pads. i would bolt the cage in like normal, then go around and weld the pads in. just my theory though, i'm sure there is some internet chassis expert that will say i'm dumb and don't know anything.
once you get into welding on the stock floor pans you will understand my reasoning behind this. they are very thin and could use all the help they can get. a through the floor subframe connecter that connects the main hoop to the front pad would really kick ass too.
oh yeah, if you got 3k you could just buy my car with the cage already in it. it would save a whole lot of time.