I've looked at the OEM rollbar and ways to replace or strengthen it. As you can see from the pic that I took on the xfire roadster, it looks like any replacement will have to go to the same space where the OEM part is right now. No space to extend it further to the side or towards the back unless I have no plans on raising or lowering the top.

Does anyone know how far down the rollbar go and how it is secured?

I did see something (see pic w/ chrome) on a Miata that might be an option. I'm guessing the bars that goes vertically alongside the seats goes all the way down and is bolted/welded on to something. Although, I have no idea if this is structurally sound and does provide protection.

Does anyone here have any ideas on how to strengthen/replace the OEM?