DGatzby,
I've got the UPR brand oil catch can - engine block mounted. I even installed it myself - my first step up the mechanical competence ladder of Hellcat success. I get 1-2 ounces between six month oil and filter changes - and I ran a couple of road course weekends. If anyone ever asks me what it is - pretty chrome - I'll be sure to tell them it adds 37 HP.
This link I got off the aadperformance.com website under the technical articles. The author thinks a catch can on the driver's side and a second one on the passenger side is merited. I don't have any idea what side it should go on, but if it would add another 37 HP I'm in!
https://www.shophemi.com/images/media/p-2273-arrington_ccv_bible.pdf
Best,
Finface