It's a casting, with a typical rough cast finish.

I really dont see the problem ?

I'm sure you could have had either polished at extra cost if the external appearance is so important.

Engine blocks, cylinder heads and many other cast parts look equally as....cast

Out of interest...

Is that turbo using the genuine Borg Warner turbine housing with the integral wastegate that the units normally come with ?
Or maybe reason it doesnt say BW, is it's an aftermarket piece to accommodate the use of an external wastegate ?