[dub_it]

So I'm looking at buying an E46 330i (probably '03-'05). I plan on installing / upgrading to a Dynavin touchscreen nav. My question is, if the car does not already have a navigation system in place (along with the trip computer), will I be able to hook up any pre-installed wiring to get the trip computer function, or will I be SOL if it wasn't already a feature w/factory nav? I've searched quite a bit so far, no luck... thanks for any input.