Hi WJ,
Thanks for the reply. I can handle the SW without issue, but I think I might sub out the amp job. That might be a little over my head. I have put in a lot of radios and CD players over the years, but nothing like messing with this head unit. I do have another question? If I change out the SW and amp....I still have to change out the speakers right? I'm assuming that the stock speakers won't be able to handle the increased power. If you have some time, I will take and thankfully accept any guidenence that you can offer. Thanks

WW -

My pleasure to help.

The Earthquake SWS-8 subwoofers are drop-in replacements. They fit exactly, right down to the screw holes matching. Very easy. They are available in 4-ohm and 2-ohm versions, so you need to be aware of what you are doing with your amp. I'll expand on this point if you need, just let me know if you are or are not aware of impedance matching between speakers and amp.

The amp is somewhat more complex, mainly because it's not easy to get a line level signal from the OEM BMW head unit to an amp. I selected the Blaupunkt PnP amp because it is designed to work with OEM head units, and you can purchase an accessory cable that literally plugs in to the back of the BMW head unit, intercepts the line-level signal, and delivers it to the amp with a plug properly terminated to interface with the amp. This is highly recommended; much, much simpler than engineering a one-off connection.

Really, if you have the standard audio system, as I did, no upgrades you make will help much unless you upgrade the amp; it is so completely underpowered. In my view, assuming typical speaker sensitivity, you need something like 40 to 60 watts per high-end speaker and no less than 200 watts covering the low end to accurately reproduce music at satisfying volumes. The Blaupunkt PnP 555 (if I recall the model number accurately) has 45 per 4 channels plus 300 watts to the sub at 2 ohms - you could use more but this is enough. The stock amplifier has something silly like 8 watts per channel plus 15 or 20 to the subs.

Hope this helps - please feel free to follow up with more questions.

Hi WJGreer,
I have a 535i with stock music system and I want to upgrade the sub and amp. I have a couple of questions if you have time to answer some.
Are the 8 in subs you put in your car drop ins for mine? Meaning I can just pull out the OEM ones and replace with the 8 inch ones? What about the amp? I am looking for something that I can do myself without any modifications to the car. If that is possible...do you think you can give some instuctions? if you have time.

Any advise or time you can give is greatly appreciated.

Thanks

WW