Think 16v has 28splines on g/box input shaft, and 8v has 24 (smaller). So match it to whatever box your using,they all fit the crank the same...
Thats the friction disc, the gti flywheels are all the same.
wont that be already what i have though
Yes, but unless you want your car off the road whilst it's being done then you need to get another one to send away.
To be blatently honest mate you shouldn't waste your time or money as it's going to make negligable difference to an 8v gti. Save your pennies for an engine conversion if you want to go quicker.
If you really want to do it then look up a local engineering shop or if you can't find anyone then try hotgolf on clubgti