348 Front Bumper Removal

I have read the threads and located the bolts. I am trying to remove a faulty alarm siren which I believe is behind the bumper. However I have a neat row of pop rivets along the bottom, three central and two each side, My bumper looks too short to fit under the tabs on the floor pan. If I remove the eight bolts will the bumper tip forward enough to get my hand in to remove the siren, or do I really need to pull it forward to clear the bolts? In which case I will need to drill out the rivets.

 

Thanks, I've looked at all the usual places, it sounded like it was in the LHS wheel arch behind the foglight, but it's hard to tell once you get close! But it wasn't in there. It's definitely up front somewhere, I'm struggling to even find the wiring for it. But on a plus point I could clean up all the trays and vents I have removed so will look better when reassembled.