I dont know the exact numbers on the weight differences but the 318 is a little lighter.
I think the flywheel is near the same but the clutch/disk due to smaller size, its lighter.
In my opinion, will have a negative performance if heavier...need more energy to turn heavy stuff.
so lesser responsive engine...recommend to put lightweight flywheel if going larger clutches than 318.
my setup was like 11lbs lighter than normal 318 kit.
good luck