[MasterC17]

I purchased a set of 3" Catless Downpipes from MMP Engineering and wanted to review my experience with installing them. I installed them on my 2011 335is Convertible.

Here they are out of the box:





Here's some close-ups of the welds and the bungs:







Stock Downpipes removed:



MMP Downpipes (Not installing rear 02 Sensors):



And here they are installed in the car:







And finally a video of the sound (rev's to 3.5k RPM):

Installation was easy, it took me longer to get the stock Downpipes out then to install the new ones. Fitment was spot on, I didn't need to make any adjustments and the hardware went in without any trouble. I threaded all four 02 Sensors into their respective bungs and they went in without any trouble at all.

Overall, I am very happy with these Downpipes! As was with the other products I have purchased from MMP, fitment was perfect, installation was simple and easy, and the car ran great when I was finished! Oh, and not to mention that nice power bump too!

[langsbr]

You should reconsider not installing the rear o2s, or at least one at a minimum. Even though you may have the code disabled, it only disables you seeing the error code, but the DME still uses the secondary O2s for adjusting trims. I didn't believe it at first, as they are supposed to be only for catalyst efficiency, but multiple developers for the DME XDFs have confirmed they are needed.

[MasterC17]

Originally Posted by langsbr

You should reconsider not installing the rear o2s, or at least one at a minimum. Even though you may have the code disabled, it only disables you seeing the error code, but the DME still uses the secondary O2s for adjusting trims. I didn't believe it at first, as they are supposed to be only for catalyst efficiency, but multiple developers for the DME XDFs have confirmed they are needed.

Good to know, thanks for the heads up! I'll put them back in then.

[HCMW Adam]

Good looking dp’s

[Jeff@TopGearSolutions]

Originally Posted by langsbr

You should reconsider not installing the rear o2s, or at least one at a minimum. Even though you may have the code disabled, it only disables you seeing the error code, but the DME still uses the secondary O2s for adjusting trims. I didn't believe it at first, as they are supposed to be only for catalyst efficiency, but multiple developers for the DME XDFs have confirmed they are needed.

Yep, OP should definitely run Rear o2 sensors for air fuel trims.

[marcvtec]

I still have my Catless AR Down pipes installed from 10 years ago. Full seasons.
Now thats advertising !
These pipes and welds look good !, nice job.

[kafandi]

Sorry for a late thread bump but I haven’t really found too much info on MMP downpipes on searches. What’s the benefit to the taper at the end of the downpipes? Is that a 3” to 2.5”?

[Emilime75]

Originally Posted by kafandi

Sorry for a late thread bump but I haven’t really found too much info on MMP downpipes on searches. What’s the benefit to the taper at the end of the downpipes? Is that a 3” to 2.5”?

I believe it's to allow for the transition to the mid section of the exhaust, which are roughly 2 3/8"

I've also been looking for info due to the current pricing...there doesn't appear to be any, except for this thread here.

[Grimmist]

How long did it take for them to ship them? I ordered a set last week still waiting on a response from them tho.

[eastsidaz]

Originally Posted by Grimmist

How long did it take for them to ship them? I ordered a set last week still waiting on a response from them tho.

Based on the latest available information from 2022-2023, MMP Engineering (Mauricio) is generally considered to be inactive or out of business, although their website occasionally remained active, leading to confusion.

Status: While they were known for N54/N55 BMW turbo upgrades, by late 2022/early 2023, users on BMW forums (Bimmerpost) were reporting issues with communication, failure to ship orders, and advising others to buy from different, active suppliers.
Reputation: MMP had a volatile reputation. They produced high-performance "Stage 3" turbos and silicone inlets/outlets that were praised when working, but were overshadowed by frequent reports of long delays, poor communication, and some reported issues with early turbo designs.
Alternatives: If you are looking for N54 turbo upgrades now, the community largely moved on to other providers years ago, as noted in discussions on platforms like Bimmerpost and ***********.

It is highly advised not to place orders on the old website without confirming activity, as many users reported issues getting parts in 2023.

[Torgus]

Originally Posted by Grimmist

How long did it take for them to ship them? I ordered a set last week still waiting on a response from them tho.

MMP has been out of business for so long...chard your card back.

I can't believe Mauricio still has the website up. Sketchy.