As always... I take no responsibility for your actions or any damages, bodily harm, destruction, etc... from doing this mod yourself.
Here's the official MV-Tuning install video...
1. Take some masking tape and mask off what you're going to cut to protect surrounding plastic and makes the cutting line more visible. Dimensions are taken from MVT and it do NOT have to be 100% accurate as the diffuser base will cover any mistakes.
2. Here's what you'll end up with... maybe better looking, maybe worse than mine.
3. Next step is to clean up the melted plastic mess with sand paper/block or a razor blade. Not really necessary, but it gives some peace of mind?
4. Use rubbing alcohol or adhesive promoter to clean the bottom of the crash bar (the part that is exposed just past the bumper cover). You'll be sticking that tiny third piece on.
5. Now take those two rectangular cap pieces and install them as shown. The clips are reused from the original bumper piece you cut out. (I actually used a nut/bolt instead, shown in one of the later pics).
__For Diffuser Var.1 and Var.2 with the integrated F1-Style Light__
6. WIRING. Do this at your own risk, I'm not liable for fried electronics, fire, injury, destruction, etc... Use a multimeter to verify YOUR car.
**Note, Yellow is Ground, White is Parking Light, Purple is for a constantly flashing brake light, when brakes are depressed... (I didn't want that so I'm using the parking light function in place of the flashing brake light).**
7. I removed the taillight and ran the wire through the existing grommet that houses the BSM and Keyless antenna harness. (The alternative is the grommet under the left side storage bucket in the trunk)
8. Now prep both surfaces and install double sided tape, then stick on the diffuser (it helps to have two people, but manageable by yourself if you know what you're doing). Once that is mounted, you will need to use the proper size drillbit (I forgot which one I used, but you can measure) to drill into the OEM bumper using the MVT diffuser's existing holes; follow that up by using the supplied screws. You'll end up with something like this.
9. I ran into a problem w/ my exhaust hangers pushing the diffuser down and flexing the exhaust cut out so my exhaust tips will hit the diffuser, but I have a custom exhaust w/ 4" tips. I ended up trimming a small section out (kinda like the OEM bumper)
10. Here's what it looks like from inside. Remember the nut/bolt I mentioned?
11. I derp'd out and forgot to take pics of the install of the diffuser attachment, but it's simple... Double sided tape and 4 screws on the underside.