Fitting aftermarket headunit to Bose equipped c4s

Hi I am new to the forum and Porsche ownership, having bought a 2003 C4S last week. Whilst I am loving the new car the standard headunit / telephone leaves a lot to be desired and I need some of the basics like iPod and Bluetooth fitting. I thought this would be a simple case of swapping for a new double din unit, but I have been told that I need new amps and the speakers rewiring because I have the Bose system. Does anyone know either a headunit that will work with the existing amps and speakers or a connector that makes the job easier without having to effectively take the interior out? I have a pcm2 with sat nav, telephone, cd changer and Bose speakers. Secondly will swapping the headunit effect any of the dash display readings? Any help or pointing in the right direction appreciated

Welcome Craig! It is a perennial problem, because the Bose amplifier only has a fibre optic input (MOST). Also, the speakers have different impedances to standard units. There is a simple way, but it is quite expensive. Google for NAV-TV MOST-HUR. This is a device which converts the line outputs from a standard head unit, and converts them to optical signals for the MOST bus.

Thanks for that but see what you mean about the cost. If I did rewire the speakers, do I read you post right that the impedances would be unsuitable? I am thinking here that you would take an aftermarket headunit and then use the inbuilt amp to drive the original speakers by just wiring them directly back to the loom? Then tap power, ignition and gps etc from the stock loom? If all else fails it looks like it might be time to start saving, but I don't like to give in so easily Thanks

Bose uses 2 ohm door speakers IIRC, and most aftermarket use 4 ohm. I dare say they would be OK, but most people replace both amp and speakers. That said, if you are going to bypass the amp, then there is an Audioleads adapter which will connect the speaker outputs from an aftermarket head unit to the plug on the car's loom which goes to the speakers. Their part number is PC2-95-4, and they are about £25-30.

I believe that there is a Pioneer unit now available which is fully MOST/Bose/etc. compatible. http://www.pistonheads.com/gassing/topic.asp?h=0&f=48&t=1338058&mid=0&nmt=Sat+Nav+for+997

I don't think the Pioneer unit has a MOST output. I think the company advertising it must use the MOST-HUR. They say they use an inerface, and can fit 'any double-DIN unit within reason' on their web site. Edit: http://www.audiofile-incar.co.uk/index.php?option=com_content&view=category&layout=blog&id=62&Itemid=100

Thanks Richard I will try the auto leads adaptor and see how I get on. I will no doubt be back when I have a car in pieces and nothing works anymore [ ]

Most of what you need will be in the black power plug on the back of the unit - 12v+, earth, speed signal, aerial amplifier connection, etc. The only thing you will need to provide is an ignition-switched supply. If you want the wiring diagrams, drop me an email. Edit: it just occurred to me that the forum email notifications aren't working. My email is richard -at- richard hyphen hamilton d0t co d0t uk

Is it just pcm 2 Bose systems that are most or are pcm 1 systems most as well?

PCM 1 is wired conventionally with copper wires, so the answer is no - PCM 1 is non-MOST. If your PCM 1 is Bose, it is the analogue version, which was only fitted in MY2002. It is a strange system, which amplifies the speaker outputs from the PCM head unit. The upside is that it makes it much easier to fit an aftermarket head unit.

Excellent thats what i wanted to hear.

I did that conversion about 4 years ago. There maybe some old posts of here with photos I took at the times and details of the model numbers etc...(I forget now!) But basically I got round the problem by replacing the BOSE amp with an after market 5 way amp. 4 channels powering the front speakers and one channel powering the sub. I replaced the PCM2 with a Pioneer unit which powers the rear speakers. I also created extra space in the boot by removing the CD-Changer and mounting my new amp in the gap. Makes for quite a neat job and gives more boot space. I then sold the Bose Amp, PCM2 and CD Changer on eBay and made almost enough to cover the cost of my new head unit, amp and accessories. Of course it's not original Porsche any more, but it looks and sounds great!