This will apply to ANY LED bulb used for REAR AND FRONT turn indicators.

Just a quick blurb about LEDs for what it's worth:
Not all LEDs are made equal. I avoid the "5050" SMD (- surface mount) LEDs. The adverts call then 'super bright' or "10x brighter than regular bulbs". Unfortunately, that is 100% rubbish. 5050 refers to the size of the LED. The smaller the number, the more LEDs the bulb can contain. That is why you can get 20 of the 5050 LED bulbs for about $10.
You get what you pay for. For example, a Phillips brand "2323" LED is amazingly brighter than any "5050" LED. I recommend a company called Vled http://www.vleds.com/ . They carry all sizes and each bulb is clearly rated for brightness. They also carry a variety of temps from 4,000k to 10,000k to match your exiting lights. Here is a link to the LEDs I bought: http://www.vleds.com/7443-hva.html which shows specs for the bulb. It provides 320lm which is ALOT with a lifespan of 50,000 hrs! Their Triton LEDS are about 430lm.

The first thing you absolutely MUST do is apply painter's tape around the entire tail light. The tape is very thin and can slide in half-way under the tail light. In tighter areas, use a flat, thin squeegee as pictured below to be sure your tape goes BETWEEN the tail light and the bumper. When you eventually slide the tail light out and away from the car, it will drag over the bumper and scratch your paint! The painter's tape leaves NO residue on your car and is thick enough that 2 layers will protect the bumper.

Next, remove the black plastic trim piece that runs along the inner border between the tail light and the trunk opening. I used a small flat head screwdriver with painter's tape over it. Start at the top on each side, then just get your fingers behind it and give a sharp yank.

After the black trim is removed, you will see two 10mm bolts that were previously hidden. Remove them, then gently slide the entire tail light out and away from the car SLOWLY - there is a connector with very little length and you don't want to snap it off or stretch the wiring.

You can replace the turn signal bulb without disconnecting from the car, but I took mine completely off to better show the location and the 'door' that must be twisted off to get the bulb out. The space around the bulb is VERY tight and you will need to advance the blue wire as far out of it's hole as possible to give you the freedom to untwist and remove the actual bulb without dragging it against the lens and possibly knocking it loose and having it fall into the lens. It's no trouble to disconnect so I recommend you do the same for safety.

Replace the orange bulb with your LED bulb. Remember, to avoid hyper blinking you will need to add a resistor (unless your bulb states "error free" or "CAN-BUS proof". I used a plug-n-play resistor / decoder for the front turn signals but these are too big for the rear turn signals. The tail light will not fit neatly back into place with those attached. I show them here as an example of what can be used for the front turn signal, or anywhere space is not an issue.

Instead I went old-school and used the standard resistors above (50w 6ohm). Simply splice the red from the resistor to one of the wires from the turn signal. Then splice the black wire from the resistor to the other wire of the turn signal.

Next you need to make sure you don't have polarity issues which LEDs sometimes have. Connect the tail lamp socket and tape the tail light to the car it so it cannot fall out from the body. Test the turn signals. If there is a rapid blink, or if the bulbs do not light up, simply reverse the bulb in the socket.

After re-installing the tail light, if you taped well around the area, there will be NO scratches on your bumper.

** It's worth mentioning that Vled makes a "Triton" turn signal bulb that is also very bright (430 lm) and has its own decoder so you won't need to splice any wires. I used them on my 07 M and they worked great, but they are a little pricey ($135 pair).

Good work Larz. Going to FAQ this shiznit.

Any idea of what the behavior of the existing oem light would be if the same (cheaper) resistor was attached? Would it blink even slower, or nothing would happen?

TDot wrote:Any idea of what the behavior of the existing oem light would be if the same (cheaper) resistor was attached? Would it blink even slower, or nothing would happen?

LEDs require resistors due to lower power consumption. There wouldn't be any point in adding resistors to OEM bulbs and I doubt they would function any differently but if you're curious, have a go and report back.