Upgrading the LS430....

OK, I would like to add some beat to the trunk of my 430 but I first wanted to know if I can adapt the system to work with an aftermarket sub/amp setup. My 03 has the factory stock Mark Levinson system and I am pretty happy with it for the type of listening I do and I dont really see any need to upgrade the factory component speakers, I just want to add 2 10s or 12s for some more bass. 
 
Can the factory deck accept a sub output/amp control and how difficult is it going to be to get in behind it to plug it all in? Also is there a way I can add an iPod interface because I hate getting stuck switching CDs around all the time as well as having to carry them in the car. 
 
I know these are pretty basic questions but any help you guys can give me would be greatly appreciated. 
 
Thanks.

you can ad some subs to the factory system, its totally do-able. that type of install will require all the usual parts, plus a line output convertor. what this part does is it takes signal from some speakers and turns into a lower voltage signal which can be sent through an RCA into the amplifier.
 
and you should be able to ad an aux input for the factory stereo. the stereo shop i most recently worked at used to sell products from a company called USAspec. on there site it shows that your vehicle, if so equipped without factory navi or sat radio, can ad a dedicated aux input using part numbers PA15/20 toy and an adapter cable CAS LEX. now this will plug into a factory sat radio or cd changer port and confuse the factory radio making it think the iPod is a cd changer. the radio will most likely NOT show the artist and song information but this will be a digital input which will sound much better than an fm modulator would sound.

Visit Clublexus. Lots of information to do this over there.

The car does have Navi but Im sure that company makes an adaptation kit for the cars with Navi/Cd Changer as well. 
 
Thanks for the help so far, I'll check out CL at some point this weekend as well.