[dmdodd83]

Hey y'll, I just wanted to throw this up and out there for others thinking about doing this, to 'hand back' to the community I've been using for a few months now

I had wanted to do this for a while, as the previous owner somehow had decided to paint the diffuser insert in the M-Tech/M-Sport bumper body colored (instead of keeping it the more-aggressive stock matte black), and I thought 'why not make a little more aggressive/custom while doing the repaint'

For the $, the eBay diffuser/fins is a decent piece of kit, it isn't perfect (i.e. the spacing between the fins was off by say 1/8" to 1/4", but no one's going to notice!).
I definitely recommend buying their 'install kit' (a bunch of self-tapping screws, screw-clip sets, alcohol wipes and 3M tape) as used extra tape and self-tappers to hold to my bumper as want to makesure this doesn't get ripped-off.

It took a few hours to remove my bumper insert, clean/degrease, attach this diffuser part, then four (4) coats of Plastidip (prob the hardest part to get right in colder, wet 50F weather) to blend the bumper insert and this high-gloss black diffuser part together.
All in all, very happy, fun weekend DIY.

Parts procured:
+ One (1) "Fits 06-13 3 Series E90 E91 E92 E93 Rear Bumper Lip Diffuser 5 Fin Gloss Black" (https://www.ebay.com/itm/Fits-06-13-...k/282075402977) $30
+ One (1) "Automotive 3M Installation Hardware Front & Rear Bumper Lip / Side Skirt Install" (https://www.ebay.com/itm/For-Front-S.../282363340558?) $15
+ Two (2) Cans of Plasti-Dip Matte Black (https://www.amazon.com/Performix-112...=fsclp_pl_dp_1) $6-8ea
+ Degreaser (to prep the parts before PlastiDip'ing)

[6ixSpd]

So this is just a flap/piece that sticks on to the underside of the stock diffuser?

[dmdodd83]

Yep you got it, as shown in the eBay posting, it's a hard ABS finned part that looks like below, that you then attach direct to your OEM bumper (if non-MSport) or to the removable OEM Diffuser Insert (if you have the MSport/MTech bumper).

So in summary, if you have the MSport/MTech rear bumper and you've got the $, you can buy a $300 CF diffuser insert ... or you can DIY it like I did for a different look
If you have a non-MSport OEM bumper, this might be a decent mod still (see the pic on the eBay posting as this is a non-MSport bumper with it attached)

[AWSB328iM]

Horrid

[dmdodd83]

Yeah, it looks chintzy when it arrives, but once it's installed correctly (including plastidipping the whole thing in) it's quite a subtle improvement, especially given it's UNDER THE CAR, so you can't really see the whole plastic part other than the fins (which is what you want anyway).
Don't worry, I'm not going to be throwing plastic caliper covers on this fine German piece of engineering: this is a diffuser insert that I was going to spraying anyway and thought I might as well try it. Plus worse-case I could buy a new aftermarket diffuser insert if I hated it.

Also thanks for your constructive feedback AWSB328iM. How's your 328i holding up... couldn't afford an N54?

[6ixSpd]

Originally Posted by dmdodd83

How's your 328i holding up... couldn't afford an N54?

Ironic, considering you chose to do this instead of buying a proper new diffuser in the first place.

[philgli]

nice work man. from almost every angle, you would only see the fins!

[NYBulldog]

Idk man, why not have someone blend the plastics and paint it a uniform color?

[joeinsd]

Isn't this the same thing Evo owners throw on top of their cars? Smart Ebay seller marketing it as a diffuser too now.