I have these two HKS 50mm wastegates and I noticed a difference in how the "exhaust housings" attache to the manifold. One has bolt through the entire housing and screws into the manifold while the other has bolts going through the manifold screwing into the housing.

That being said, are there are real differences in terms of performance between the two?

 

I'm trying to look at the picture on a mobile device and there is a ton of sun glare, but I have seen a ton of HKS fakes. The top pic looks genuine to me but its hard to tell. Are there any stampings anywhere?

 

Yeah, they both have the HKS logo on top. I haven't seen/searched for markings anywhere else. I got them both under the impression they are both authentic. I've found promotional pictures of each from HKS, as in both styles seem legitimate, but couldn't find out details on why you'd have the different style of 50 mm without much difference.

 

Making bolts that would be otherwise impossible to do up would be a pretty good justification for offering different castings of wastegates

Personally I would use the one that works easiest with studs and locking nuts.

 

Mine looks just like the one on the bottom

 

I remember the SS autochrome "hks type" had the bolts going through the fins at the bottom.It was a snotbag to get the bolts tightened.