In my GT (got it a couple of weeks ago) the sound is a bit rubbish tbh. Do you reckon this upgrade will improve things or would I be best off replacing the whole head unit with one that has all the toys on it - BlueTooth, USB, Aux in etc?
The Bluetooth Interface is designed to work with the latest Blaupunkt Head Units. I got a new Casablanca MP56 (Check the specs Blaupunkt Casablanca MP56 ) from Halfords as they were selling them off for £50 reduced from £150. The Bluetooth Interface allows total hands-free calling and audio streaming over Bluetooth as well. Callers have commented on the fact that if I hadn't said that I was speaking to them from my car they would not have known as there is no echo and the microphone supplied is of the noise cancelling variety. The improvement in sound quality and volume over the standard fit HU which was made by Blaupunkt is substantial.
As dpat says, will only work with aftermarket an not factory fitted Blaupunct manufactured head units. However, for about £90 I've got a 50w per channel head unit that plays MP3 & WMA encoded discs, SD MMC cards, USB flash drives, and USB powered hard drives, compatible with your Ipod, with a quality Bluetooth handsfree integrated car kit
This interface works with all Blaupunkt aftermarket radios after model year 2002. I have one in my 2004 model 156. Sound quality isn't good but I think İt's usefull for playing mp3 tracks on original sterio.