[jmg]

I'm looking to get the OEM M Performance Rear Diffuser for my 340i but both shopbmwusa.com and GetBMWparts.com do not show they are compatible with the 340i. I know that the 328i diffuser is for single exhaust, and the 335i diffuser is for dual exhaust, so I wanted to order that one, but will it fit the 340i exhaust?

I was also thinking of getting the RW Carbon CF diffuser, which says it fits the 340i, but I'd rather not deal with fitment issues. They state you need to remove the bumper to install, which I hear isn't the case for the OEM diffuser.

edit: why is the RW CARBON website censored out? Bad reputation?


The Ebay Advanation looks promising, made of PP and that lists as being 340i compatible.

If anyone has any experience with the Advanation, feedback is appreciated. Do I need to remove the bumper?

[DrifterX]

The 335i M Performance Diffuser should fit the 340i w/ M Sport... if it doesn't then I guess I got a paperweight sitting in my bedroom right now

[jmg]

Okay thanks. I think I will have the dealer install it just to be sure.

Originally Posted by DrifterX

if it doesn't then I guess I got a paperweight sitting in my bedroom right now

Well, I guess you could move it to your garage, problem solved! j/p

[smithf80]

Originally Posted by jmg

Okay thanks. I think I will have the dealer install it just to be sure.



Well, I guess you could move it to your garage, problem solved! j/p

Don't waste your money. It takes like 5 minutes to install yourself.

[jmg]

Originally Posted by smithf32

Don't waste your money. It takes like 5 minutes to install yourself.

You underestimate my incompetency with a drill.

[Mjolnir63]

Originally Posted by jmg

You underestimate my incompetency with a drill.

That's honestly what I had thought at first. But trust me, you can definitely do it. I had the same question about a month ago on this forum. Save those labor money toward your next upgrade.

[smithf80]

Originally Posted by jmg

You underestimate my incompetency with a drill.

You don't need a drill. You need a small socket set and the basic knowledge of right-tighty, lefty-loosey.

[Revelator]

Sorry to bump an old thread but I figured it better than starting a new on the same topic. I'm also in the market for the OEM M Performance Rear Diffuser on my new 2017 340 M Sport. I can only seem to find the diffuser for the 335 but I'm making a big assumption that it does in fact fit the 340 M Sport frame.

I haven't purchased anything yet. Originally I was going to go with the RW version, but I can find OEM for about $100 more. Not to mention, I read that you have to remove the damn bumper to install the RW version which seems a bit excessive. I called my body shop and they quoted me a god awful $400 estimate in labor alone which is ridiculous. I'd rather buy the OEM for $100 more and install myself. Do you need a lift to install the OEM?

Sorry for the loaded post but shopping for upgrades and install has turned out to be a huge pain in the ass. Also looking into CF mirror caps, which I imagine should be a seemingly simple install. Any insight you guys have would be appreciated. I could not stand to drop $770 for the mirror caps through the dealer....

[hollandog]

Originally Posted by Revelator

Sorry to bump an old thread but I figured it better than starting a new on the same topic. I'm also in the market for the OEM M Performance Rear Diffuser on my new 2017 340 M Sport. I can only seem to find the diffuser for the 335 but I'm making a big assumption that it does in fact fit the 340 M Sport frame.

I haven't purchased anything yet. Originally I was going to go with the RW version, but I can find OEM for about $100 more. Not to mention, I read that you have to remove the damn bumper to install the RW version which seems a bit excessive. I called my body shop and they quoted me a god awful $400 estimate in labor alone which is ridiculous. I'd rather buy the OEM for $100 more and install myself. Do you need a lift to install the OEM?

Sorry for the loaded post but shopping for upgrades and install has turned out to be a huge pain in the ass. Also looking into CF mirror caps, which I imagine should be a seemingly simple install. Any insight you guys have would be appreciated. I could not stand to drop $770 for the mirror caps through the dealer....

I got the ebay version for like $100 and installed myself less than 30 minutes.

[Revelator]

I'm thinking that will be my likely course of action as well. Seeing it on ebay now for $400 but may wait it out a little longer to see if the price drops.

[DrifterX]

I installed a used (2012, I think) F30 335i M Performance diffuser on my 340i without issues and didn't have to remove the bumper. You just have to squeeze your hands behind the diffuser after you've removed the bolts to access some of the tabs which hold it to the bumper.

I took these pics to post a how to because no one seemed to have shared proper pics in any of the threads i came across... but never got around to it so I'll post em here

1. Remove the 7 bolts from underneath the existing diffuser (I don't remember the size but I believe they were 8mm)

2. Get your hand or a screw driver behind the diffuser from under the bumper to push 8 tabs out of the slots on the bumper (also see 3rd pic below for reference). You should be able to pull down the diffuser to access the tabs now that the bolts have been removed. Here's what the tabs look like when attached to the bumper:



3. Once all the tabs are out of the slots, you can pull the diffuser off easily. Here's a side-by-side comparison as well as the tab locations on the bumper. I've also noted the bolt locations on the diffuser; you can see the bottom of the diffusers in this view:


4. To install the new diffuser, you just need to do everything backwards. IIRC, I started with attaching the tabs in the middle of the bumper and worked outwards. Then screw the original bolts back in from underneath and you're done.


Good Luck!

[Revelator]

Thanks dude!! Very helpful! I won't have my 2017 340 till late Apr so I'm probably looking to do this in a few months...

[jmg]

Originally Posted by DrifterX

I installed a used (2012, I think) F30 335i M Performance diffuser on my 340i without issues and didn't have to remove the bumper.

Excellent write-up!

[CJ421]

Very nice write-up indeed!

Charles

[dsc888]

Gentlemen,

I hate to revive an old thread but I just had to chime in after attempting to install an eBay F30 diffuser onto my 2017 340ix. The seller's fitment guide clearly stated (or perhaps assumed) that it would fit a 2017 model with the M Sport rear bumper. BUT, it didn't! I bought from a seller who had sold nearly 200 of them and these were advertised as the "Taiwanese", which had superior fitment and build vs Chinese ones.

The cutouts for the slots/tabs were off by at least 1/4". The center "dip" section where the fins are located was about 3/8 of an inch NARROWER on the diffuser than on the bumper. And when I held up the diffuser to the OEM flat piece to measure end to end. It was shorter by about 3/8". There was a reason why the official BMW sites only list the 335i and the 328i.

Needless to say, I sent my diffuser back to the seller who gave me a full refund. eBay also refunded me the return shipping so it was just time lost. So, those with the 340i modes from 2017 need to beware of this potential issue. I noticed that MOST sellers do not list the 2017s as compatible. My guess is that those listing are unaware of this issue. I e-mailed my seller and never got a response. Every YT video show an easy fit once you pop off the reflectors, which I did. But non of those videos are of 2017 340i models.

If someone has successfully ordered and fitted a non OEM plastic rear diffuser onto their 2017 340ix, please let me know. I'm still in the market for one.

[Das440i]

I purchased the RW Carbon version for my 440 (sorry not a 340ix) but it's still a 2017 and the fit was perfect. Installed in less than 15 minutes.

If someone has successfully ordered and fitted a non OEM plastic rear diffuser onto their 2017 340ix, please let me know. I'm still in the market for one.[/QUOTE]

[skw]

I ordered and installed the one from advanation on ebay. No issues w/ fitment nor installation.

[7iM3less]

Great write up!

[dsc888]

Thanks, Das440i and skw. That's great news! I was beyond shocked when mine wouldn't fit. I've installed bodykits before so it's definitely not from lack of experience. Maybe I had a bd unit but I highly doubt it. Maybe I will take a 2nd try and see if I have better luck this time from another vendor. I'm just nervous that there might have been a silent running change at BMW for 2017s.

[dsc888]

Originally Posted by skw

I ordered and installed the one from advanation on ebay. No issues w/ fitment nor installation.

I only see a Quad Tip Rear Diffuser over at Advan for 2012-2014. Is that what you ordered? Thanks.

https://www.ebay.com/itm/3-Series-F3...-/172873205222

[skw]

Originally Posted by dsc888

I only see a Quad Tip Rear Diffuser over at Advan for 2012-2014. Is that what you ordered? Thanks.

https://www.ebay.com/itm/3-Series-F3...-/172873205222

No, single tip on each side

http://f30.bimmerpost.com/forums/sho...9&postcount=19