From what i can gather the GT clutches and the other models are 190mm and the G40's are 200mm.

My engine is killing the clutch in the lower gears, is there a big difference between the two in terms of how much abuse they can take?

If i used the G40 clutch what else would i need? Are the flywheels and clutch plates different?

Thanks

you just need a clutch kit which comes with the friction plate and cover plate. The flywheels are all the same.

Thanks, is it right that the g40 clutch is the same as one of the mk4s clutch except without the G40 tax?

there is an early mk4 16v clutch that is the same yeah, I don't know the part code though. I believe it is a little bit cheaper.