Flywheel of the EXEDY CARBON-R and COMPE-R has many holes, but how much lighter is it?

The weight of the flywheel is recognized as affecting the engine response, and the idea of inertia moment is important for this.
What affects the engine response is the “inertia moment“, which is a characteristic that tries to keep on rotating.
“Weight” is not completely wrong, but even with the same weight, “inertia” will be completely different even for the same weight if the “weight” is distributed close to the axis of rotation, or if it is distributed along the rim.
If you are considering the response to be important, it is recommended to select the one with low inertia.
Following is the comparison of the inertia of EXEDY products using the product for “R34 GTR” as an example.

Genuine (single)100100100
CARBON MULTI (twin)433642
COMPE-R (twin)435843
MULTI (twin)488050 or more
CC=clutch cover, PP=pressure plate, IMP=center plate, FW=flywheel, CD=disc