Every single available upgrade on the market, for those engines!
As for the gearbox, stronger output shaft with reinforced and longer pignon of 5 th and 6 th gear.
Clutch has stronger basket with special disks and stronger springs, what is also resulted in the need of using a bigger and billit clutch housing.
Rods were replaced by steel H beams.
Special pistons to lower compression ratio.
Also a plate under the cylinder is used.
Two racing camshafts, special for turbo application.
Then of course, manifolds and (very big) turbo.
Intake plenum with 4 additional injectors (total 8 injectors).
Very big intercooler and intake dump valve.
Exhaust with blow off valve, seperately.
Big oil cooler.
Complete dry sump system with airoquipe lines.
+ a lot of stuff I am forgetting at this moment.