Depending on how deep your pockets are you could look at the Saenz gearbox.

Contact Pig off here as he has one on order for his Mk2, they are rated to handle shed loads more than anything else available.

Last time I priced a Tractive it was £8500 so not exactly ideal for everyone, the Sadev was much cheaper but this was for NA applications too and not sure I'd fancy either being that I believe they are not designed with the massive torque some engines are making.