I know i had many questions about the rattling sound coming from my transmission when i first got my G until i learned it was because of an aftermarket flywheel

i just stumbled on this page and thought its pretty good at explaining why the flywheel rattles when you replace the OEM dual mass flywheel with a solid aftermarket flywheel

http://www.uucmotorwerks.com/flywheel/gear_rattle.htm