Well, after meeting with MMW on Monday this week it was decided that they would re-engineer the frame jigs to allow for the extra length of a 6 speed transmission into my build.
Previously I was told that only a 5 speed would fit and therefore I went ahead and bought my RA geared 02 WRX 5 speed. After searching for LSD options for my 5 speed, I concluded that I could spend close to the same amount of money and get a 6 speed that 1) was stronger 2) had a superior oiling system 3) already had a LSD.
I met with the owners of MMW, Bill and Danny, and explained that future TR-42 buyers that planned on using a Subaru engine with 300+ hp would more than likely want to have the 6 speed available as an option and it would be nice for them to make that possible - They agreed!
So - I have a RA geared 5 speed to sell. (Or I may save it for my friend that is planning a lower powered TR-42)
Now I have to decide on which 6 speed. I'm leaning towards the 07 STI due to the taller gears in 2-3-4 but if I found a good deal on a 05 or 06 I could live with that too.