i dont run speakers in my parcel shelf because i run two type x subs which would interfear with the speakers. I am thinking of making some sort of enclosure for some speakers, not speaker boxes that sit on top of the parcel shelf but some sort of enclosure under the parcel shelf, anyone done anything like this before?

I guess there's no reason why you couldn't make a box attached to the underside of the parcel shelf.
Generally the parcel shelf isn't very flat so it would be a pain to get a good seal though.

They will need to be a reasonable size. 6 litres each maybe - Would need to run some calculations.

I don't have the problem so much as my subs face forward - didn't like the idea of them giving my bootlid the massage instead of me.

my subs face forward also, i mite just chuck the speakers see how they go and if the subs interfear with them then worry about making an enclosure. the only thing is my sub box is rather large and there is not much room between the parcel shelf and the top of the sub box.

Don't bother with rear speakers.

Tell your rear passengers to harden the f**k up, and enjoy the bass.