You should also take into consideration that the 6mt is 60+ lbs heavier than a 5mt. In a 1800lb car that is a lot of weight to hang off the rear most portion of the chassis. There are over 10 different companies that make motorsport gearsets (we've worked with 5 of them) for the 5 speed, not including PPG, so the options are out there. If you are building one to drive on the street with ~300hp, the RA gears would work very well. Even the 06+ Impreza or any Legacy GT gears would be better than 02-05 WRX, but the ratios are much less desirable than the RA for a sports car.