Maybe when one considers getting a base gearbox overhauling it and then modifying it and finding a Nismo gearset etc ect this would end up being a better option.http://www.saenztransmissioneurope.com/data.html
Saenz Transmissions are pretty good and cost effective because unlike the linked page which is the sales and service outlet the Transmissions can be more cost effective because they are made in Argentina, Argentina is not a backward place when it comes to some not well known but surprisingly good quality KIt one of their say TT3 series transmissions just may end up a cost effective option.