My style bar conected to that hole.
I had to open a litle for the screw get in. Then with some pacience put a nut under it.
You have to remove the seat belt for more clearence to put the nut under it.
Hi
I have just retro fitted the same OE cabin brace and procedure is easy but fiddly.
Remove trim and then the seatbelt reels.The use M10 bolts, mine with 70 but longer will make threading the nut easier.Place brace in position insert m10 with a washer at top and then reach hand underneath via space left from removing seatbelt and then use washer and or spring washer or nyloc nut and then fiddle around to do it up real tight...I used a M10 coach bolt with a domed head in case when car was left some bright spark/scrot decided to remove the bolt and take off with my cabin brace.
The you will need to cut out a section of the trim at the top to fit around the newly fitted brace bar, again this is easy as plastic is thin.you will see how much you need to remove.Once you have cut the trim it all refits as before and you will not notice that trim has been cut,looks like factory fit.
Then you buy an OE wind deflector and scratch your head 'cause it won't fit as it should.Why mazda did not realise this I don't know?
Good luck Giles