[Mathew87]

I did a popular change to my pre-LCI E90 by installing the blackline tail lights. I went with the TYC version because it is lightly smoked and I feel that it looks better on my silver car instead of the clear OEM blackline tail lights.

However, after installing them, I figured that the P21W bulbs were unable to truly look like a yellow turn signal while activated. And the well-known PY21W true yellow bulbs do not fit the bulb socket because of the 150 degree pin angle, instead of the 180 degree pin angle present in the socket.

After much search online, I was able to find the "unicorn" of turn signal bulbs at a physical parts store by sheer luck: a P21W bulb with BA15S socket (180 degrees between pins) and yellow coloured glass. For the equivalent price of just 50 cents a piece (this being Eastern Europe). And so I thought about sharing the brand I found, along with a picture of how it looks installed on the car.

There is also a Ebay vendor selling the correct bulb for the pre-LCI blackline tail lights, using the following description:
382 BA15s P21w Amber Orange Indicator Turn Car Light Bulbs Opposite Pins 12v

Please bear in mind that this is a OEM-style solution that does not require a change in the technology of the bulb (like going LED) or coding out anything. It's just plug and play as originally designed by BMW.

[M-technik-3]

Nice heads up, I love my blacklines on my e91.

[Mathew87]

I realized that I forgot to post pictures with the P21W yellow bulb, next to the P21W clear bulb, to show that their pins are indeed placed the same, at 180 degrees.