Does anybody know if low profile subs are good under the seats 91 frank

 

I don't think there is enough room for a cone under there. There is actually more room behind the driver's seat with it all the way back than there is underneath it.

Braineak (admin here) has some old pictures floating around of one he did that fit in the driver's corner of the trunk really well. I think they are on Miataturbo.net, our sister site.

HERE, I found the one he used: Mazda Miata MX 5 Custom 10' Subwoofer Trunk Box Sub | eBay