If it's anything like the last model (and I'm 99% certain it is), then there's just the usual ISO connector with high level outputs to the speakers and little else. No RCA's for an external amp or anything like that. Having said that, the unit is probably a Blaupunkt and actually not half bad.
I went to the effort of upgrading the speakers in my previous model 4x4 and also the clarity was slightly better, there's a very good compromise setup built into the stock setup that is hard to improve upon without a fairly considerable investment. I had to then install an under-seat sub and this picked things up a little. But overall I wished I'd left alone. If you want to really improve things then by all means do a full ICE upgrade with components, but don't expect the convenience of steering wheel controls and the like. I will leave my current 4x4TA alone, although I might try popping that sub back under the seat, just in case!