Hello mate,
I wouldn't bother with an FM modulator - they're really only good as a last resort. A proper, plug-in solution is definitely they way forward.
Get yourself a Denison iPod car kit - will cost no more than £100 - well worth it in my opinion.
It'll plug straight into the gamma unit (and therefore work as a multichanger) which will allow you to control iPod from the headunit, give text display on the headunit etc. It will also allow you to charge on the move.
Fm modulators are ok, but there is a significant drop in SQ. I use my iTrip if I'm going in someone elses car and they want tunes. Otherwise, I'll always use a plug-in system
Denison link here
http://www.dension.com/icelinkplus.phpYou want product code ILPRVW8CR1