You're better off buying a light part than modding a heavy part. The light part was manufactured to be like that, I wouldn't modify a heavy part unless you Know where the stress areas are. I got my mod down to 8.5kg's with no modding other than cutting tyre tread. You just gotta think about the parts you're buying, find the comprimise between weight and strength. E.g, front wheels don't take much stress/bashing, so you could get something like a dob rim on a viz/koxx/neon hub maybe.