If you modify the engine to increase power only then do you need to upgrade the clutch.The upgraded clutch would be stage 1 stage 2 stage 3 etc depending on the power the engine makes.You will have to upgrade the flywheel as well.
If you are changing the clutch for the first time, go with MGP,Daikin(exedy now) or Asco (aisin).
Change your flywheel if the teeth on the flywheels are worn out.
I'm using [PCH Valeos Clutch set+ MGP Fly Wheel+ MGP Releaser Bearing] bought in Hyderabad in Dec 2011 @ Rs 1300+Rs 750+Rs 650 for my M800, for the past 20K kms, since I couldn't source an ASCO one due to Tsunami in Japan at that time.
Mech said I might see a jerking after 5K km with Valeo. But here was the difference : PCH Valeo, Maroon colored packing is an OE for Hyundai, was Made in Korea and difficult to source one for M800, was really a feather touch, my mech got shocked after instanllation. The normal Valeo in green packing (I guess it was Made in Japan (Pl. dont mistake me, Japanese spares are even the best in quality) on the other hand might jerk after 5K kms.
After 20K kms with PCH Valeo its 50% hard now with my bad half clutch driving coz of less leg room in M800.
My knees had a very bad experience before this Clutch upgrade and later I got Power Brake (on my dented car:-)).