hi i got a monitor from ebay to put in to the space above the ashtray, below the heater controlls (mk4 astra) Ive seen this done b4 in magazines. my unit fits as it seems to be standard DIN? size. BUT, it wont push all the way back and sticks out about an inch. there is some plastic sheet like thing in the back? what the hell is it? what does it do? can i modify it a bit? thanks lads.