DDM tuning hids normally have bad reviews. My friend recently got them and in less then 2 weeks they failed. I told him where to go for HID's originally and he said that he could get the cheaper at DDM tuning. All said and done he wish he had listened to me from the start and bought them from a reputable company.
DDM Tuning's HID exchange policy also requires you to pay $20 for an exchange even if they have failed prematurely. It's claimed to cover the cost of shipping and administrative costs. So if you have a HID kit fail from DDM tuning your $30 kit + Shipping now turned into a $50 Kit plus shipping and you have to ship it back to them which is going to cost you even more. All said and done you have now paid over $60 on an HID kit if it fails and you could have got a legitimate kit from a quality company for just a little more. You would also have a hassle free return policy if in fact the kit failed prematurely.
There will still be people here who have had kits for 3 years - 5 years and whatever and thats great, you are the lucky ones. I can also list about 10 people I know who have had them and had them fail.
On this particular BMW regular HID kits won't work anyway unless you have the car coded.
So you need to buy a CANBUS HID Kit or it will throw errors or not work at all. The only reputable HID kit I've seen here is the HPB HID kit. There are few other vendors selling lighting and hid kits, and they also have very poor reviews from time to time even here on E90. HPB is www.highperformancebulbs.com
for those that dont know. I would give them a shout if your looking for any LED or HID's.