Longer 5th for boxer gearbox
I am currently trying to work out a plan for a project car on paper to see if what I would like to do is achievable. Would anyone know if a longer 5th gear is available for the gearbox used on the 33/145 boxer engines? I am not even sure if the gearboxes are the same on a 145 1.7 16V and a 33, but I'm looking for a way to make the rev-happy gearbox a little less revvier and capable of coping with more power. Are there any other gearboxes that fit onto the boxer engines and comply with the mentioned requirements? Thanx.