Hey everyone, I've been scanning through the past threads for hours now and I haven't found the answers I'm looking for, so here goes:

1) Can I install an aftermarket head unit with the stock speakers and navi? Do I need to modify anything (besides making a panel to go around the aftermarket unit)?

2) I have a 99TL and would like to upgrade to the DVD navi, does alpine's DVD navi plug-in to the existing screen? will it take commands from the screen or do I need to use the remote?

3) The Alpine CDA-W550 has an audio interrupt input (found it when looking at the installation guide). It says it's for in-car phones...can I use this for the navi? Will it just mute the front speakers or all of them?

Thanks all,
Tommy