We had a 2011 come in yesterday with these headers. Dude, for $450 they're kick ass. I sell Kooks and Stainless Works all day long which are no comparision quality wise, but dam you can't beat the value of the OBX. Not only are they 304 SS, but they're polished as well- absolutely beautiful.
The connection pipes are exactly like Kooks and SW, and feature a ball flange style connection to the collector which NEVER leak.
The hardware is even nice. The 4 bolts that connect the connection pipe to the collector feature springs which apply constant pressure to the nut on the other end ensuring a tight connection after thousands of heat cycles.
As mentioned before, you will need some 02 extensions. I just extended his with wire, solder and heat shrink. Took me 20 minutes. I extended them 12" and loomed the wires and they work fine.
DO NOT use the supplied, 2-pc graphite dog shit gaskets. GM MLS are THE BEST. When you remove the stock manifolds, take your MLS gaskets and hit them with some steel wool just to clean em up. Throw em back in, good as new.
Fitment was nice as well. Only one primary on the driver side hit the motormount pedestal. I was not concerned, and I am sure after they get hot, they'll "clearance" themselves
All in all, 8 out of 10. We're even considering becoming a vendor.
Erik@Lashway