the GKtech stuff is normally pretty good i have not really ever heard of any complaits on NS which is where Greg sells most of his stuff. Reason it look shitty on the inside is because it's welded on the inside, pretty much all the other dumps (Advance, CES) are only welded on the rear of the flange and not on the inside.
If you get your money back go and get an advance one piece, they are as good as CES IMO and they are in Adelaide.
http://www.advanceheaders.com.au/