i am about to change the box in my 93 wrx due to buggered syncro's and want to keep my 4.111 rear diff.after checking what boxes fit some have different 5th gear ratios.which is best for a slightly higher top end is it the lower number ones or the higher - 0.825 or 0.972 ???

 

Lower the number means more speed

 

http://www.catherineandken.co.uk/sti/trans.html

Have a look here, add your ratios into the calculator and see what it says.

But any box will fit, and my advise is to get a newer 754 box and keep the rear diff with it.

752 / 754vB is Jap usually 4.111
752 / 754vN is UK usually 3.90