One perfect example is the 3-series coupe, years 2004 and above. (E46 only) In earlier model years, the headlights lens can be taken off with ease and so if you wanted to install angel eyes into your headlights, all you would need are the LED/CCFL rings themselves, a handy screwdriver, and access to YouTube for the countless DIY guides.
However, in the 2005+ models, the headlight lenses are securely glued together. If you want to install angel eyes, you would either have to bake your headlights in the oven (if they are OEM and yes this step is unavoidable) OR completely replace the headlight assembly and buy an aftermarket kit. I would advise that you just pay up and get a decent kit because in my experience, people who have baked their lights to loosen the glue to take apart the lenses have regretted the decision later on. The glue will not go back 100% the way it was before you baked it and a few people I know who baked their lights went through a car wash and their headlights fogged up inside.
Pictured below is a '05 325Ci's stock headlights. Once the DEPO HID kit with angel eyes comes in, we'll show you how to remove the stock headlights and how to install the new one.
