As far as CD changers go most if not all stereos now come with a SD card slot. You can put a crazy amount of music on an SD card. When I went to an RCD360 I thought I'd miss the CD slot. I don't at all.
The best bolt in roll cage I have seen is the SafetyDevices. I had two of them perfect fit, amazing really. FIA certified too. You could buy just the rear cage portion. If I was to want a roll cage/roll bar today I'd have one custom fabricated.
I agree with Jay about roll cages in street cars...
When I first saw the GR Yaris I about wet my pants. This Crayola GR doesn't do it for me. When they add stupid mark ups to the price the R will end up being a better deal. I'll keep happily driving my MK6.