Neverending search for rollbar clearance

My '99 came with a HDSDD bar. I've still got my '91 that has a M2 HDHCSD bar in it. According to Bethania, the HDHC bar is 1.25" taller than my HDS bar. I removed the foam cushion completely from the stock seat in the '99 and was able to get under the roll bar (see attached picture), but I'm not WAY under it.

So the question is: Will a hard top add safety if I keep the HDS bar? The pictures I've seen of a rollover all result in the font winshield giving up. What happens if a hard top is on the car? If a hard top will not really add much safety, wouldn't I be better off with the HDHC bar from the '91? I'll be adding racing seats at some point if that changes the answer for any reason...
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An 1.25" increase in height sound like the way to go. Keep in mind the hardtop is plastic/fiberglass it might help but I sure wouldn't want to count on it.

The only thing I can envision the hard top doing is maybe help keep stuff from coming into the cabin, but it might also just fold in and trap you...

The hard top would likely break in a roll over if the A pillar or windshield frame collapses, but it will keep your hands and arms in the car and from being crushed.

Lots of open top cars require arm restraints for this reason.

Chris

Holy #$Q@! Ok, so HDHC it is. That makes me want to add the front cage add-on too. Can that be added to the HDHC bar as a bolt in piece or does it get permanently welded in? Thank you for that video.

The hard top is like a plastic lid on a can full of marbles. Shake it hard enough, and stuff goes flying...
My guess is Mazda designed the mounts to break away before hard top collapses on itself and intrudes into the passenger cabin. Not sure what happens when the top is bolted into place permanently like on Spec Miatas.

Never seen a hard top come completely off in a SM crash video. If it's bolted in both front and rear (required for SCCA and NASA), that's a lot of fiberglass to break through.

The writeup on the pointy board says that guy was running front latches only. No rear latches, no bolts front or rear - the top probably popped off like a spring once the windshield frame was bent and the front latches let go.

Edit - found a frame in the youtube video at 1:18 where the top was off the windshield while the car was still upside down. Need to find a way to attach.

http://http://www.dfwmiata.com/album.php?albumid=65