Pongo, sorry I am so grumpy...
The MK 103 installation has been a favorite of mine since I built a Monogram 1/48 Fw 190 as a kid that had the MK 103 as an option. When I started flying Warbirds, I couldn't understand why we didn't have it in the game, so I went on a hunt. And I found both US and German authors saying the MK 103 was on just a few planes that were modified and tested in Germany, and not found satisfactory, so the project was cancelled. The rockets were a winner though, see the other thread I started about that.
About MW 50 on the Fw 190A, it's been a personal crusade of mine to try to find some solid information on it, so we could get in Warbirds. I've bought all kinds of books, gone to the USAF historical archives, talked with a guy who went through the RAE archives. And all I've been able to find is a couple of prototypes. No flight test data, no information on production numbers and dates, no Rustsatz number and no engine data other than a 2100 hp claim (which is sometimes also applied for the D-9 which has a completely different engine).
The thing that clinched it for me is the A-8 handbook - it goes into detail on the boost systems. There was a supplemental petrol injection system that was referred to in the past tense, a boost override system (which gave equivalent performance to the supplemental petrol injection), and a GM-1 system. The boost override gives the performance that some authors attribute to the MW 50 system. And the GM-1 system matches the physical description that some authors give for the MW 50 system.
I'm pretty sure that somewhere along the line, somebody (RAF, Jane's?) mixed up MW 50 with one of the other boost systems, a few authors used this information in their books, and here we are...
I'm still talking with some guys from Ruy Horta's 12 O'Clock High board about the subject, maybe we'll find something.
I haven't tested the AH Fw 190A-8 above 8km to see if it performs like a GM 1 plane. That might be something to ask Pyro for. No production figures on that one, but it was common enough to merit a Rustatz number (R4), and there are records for many prototypes with that system. Also it helps the 190A in an area where it is truly deficient - fighting above 25,000 feet.