Well the new OS has been giving me problems with my headunit. How do I revert back to OS 3?

 

You cant do it...well at least you cant do it easily without losing your backups etc..search online if you are that keen. My x305 works perfectly fine with my iphone 4

 

You can also try jailbreaking and in cydia install afc2add which addresses alot of USB issues. And you can downgrade the bootrom on the 3G doesnt have to be signed by apple.

http://www.felixbruns.de/iPod/firmware/
download 3.1.3
and google how to put the phone DFU mode.
iTunes saves dates of your phones backup. With that being said you should have one preupdate of 4.0 other wise as stated you cant use a restore from a 4.0 platform phone

 

I have the Alpine iDA-x001 and I'm having major issues with iOS 4.1 (and iOS 4.1) as well. I've reset the phone, I've reset the radio nothing has changed. I've been told that the problem is with the stock cable, you must use the high speed alpine cable instead. Due to may laziness I haven't felt like taking out my radio to install the new cable.

 

Sorta off topic, but since alot of you guys have the IDA-X305s...
Do you guys have issues closing the radio cover door without the knob getting in the way?
I have the IDA-X200 and the older model's knob doesn't really agree with radio cover door. I contemplating whether or not to upgrade to the 305S.

 

I wish I had never update the os on my 3gs. The pause every 30 seconds or so is just too painful on my pioneer head unit. I may do the downgrade if Apple doesnt fix it with the next update.

 

This thread is comforting (yes, misery loves company) I thought it was just me. I have given up using my iphone 3g w/my IDA-X-305. It pauses all the time when I can actually get the unit to recognize the phone which isn't all that often. Updates did it for sure as I never had problems until about September or so.

No Limitz - I cut my radio door so the knob would fit.