Sure it's not STOCK. This card default run at ~23.x Mh/s. For 28.x Mh/s you have to modify the BIOS as I mentioned above.
For your concern about part/build quality I have to say : Slightly yes.
I got my hand on 2 mining cards : ASUS MINING-RX470-4GB (Hynix) and ZOTAC P106-100-6GB (Samsung) and they both "look cheaper" than normal gaming card.
As opposed to the Sapphire "mining cards" which appear to be standard Nitro parts with the video circuitry and connectors removed (except for one DVI connector on SOME models), and the mounting bracket changed.
Mine even still have the "Nitro" stickers on the fans....