[Ben Richards]

Hey team, Merry Christmas!!!

Five days ago I started this project - install ARM Motorsports catless downpipes in my 2016 F10 550xi. Yes, I know this project shouldn't take that long...

I was buttoning up this afternoon when I noticed something bad . While moving the brace to re-install the heat shield, I got too froggy and broke some connectors (circled in red).

What are those hoses that run longitudinally on top of that black brace across the heat shield? Any idea how to fix the broken connections?

Thanks!

BR

[Unspec]

Looks like part numbers 1 and 4 on this diagram:

https://www.realoem.com/bmw/enUS/sho...diagId=11_5160

I'd also replace gasket/o-rings 2 and 3 (2 each) while you're in there, might as well.

[Ben Richards]

Originally Posted by Unspec

Looks like part numbers 1 and 4 on this diagram:

https://www.realoem.com/bmw/enUS/sho...diagId=11_5160

I'd also replace gasket/o-rings 2 and 3 (2 each) while you're in there, might as well.

Yup, right on. Parts ordered. Thanks from me and the Mrs., who is happy to hear we won't have to get the car towed out of the garage...

Merry Christmas!

BR

[Ben Richards]

While those parts are on the way, I figured I'd provide a short write-up. Rather than a straight-up step-by-step DIY, these are my impressions from attempting this installation myself. Appreciate y'all - Happy New Year!!! -BR

ARM Motorsports provides installation instructions at this link, and there's a YouTuber named SplittMods who recorded an installation video as well.

Using the ARM instructions as a reference, my highlights are as follows:

Step 8: Be gentle here. On top of this bracket run the crankcase ventilation hoses whose connections I broke. I was too rough, and the plastic connections just gave way (see below circled in red). Also, there are cheap plastic "brackets" that snap onto each end of the black bracket you're loosening/removing to get to the heat shield. These plastic "brackets" neatly hold the O2 sensor connections. I snapped both of them into many pieces .



Step 9: I bought two O2 sensor sockets before finally buying the correct one on my third attempt. You need a deep socket with a wide channel for the O2 sensor wire.



Steps 16, 17, and 18 should be in the order 16, 18, 17.

Step 23: You're trying to get the downpipe's integral bracket off the threaded stud. This requires about an inch's-worth of play to pull the downpipe bracket off. Needless to say, there is almost zero play, so this tough.

Step 24: Again, you need some wiggle room here to separate the downpipe from the midpipe (the downpipe inserts into the mid-pipe about 2 inches'-worth), and you don't have any (wiggle room, that is). So...

Extra Step: Detach the exhaust from under the rear of the car (while supporting it, needless to say...) and pull the whole exhaust system backwards an inch or two. This will allow you to get the downpipes out of the midpipes (Step 24), thereby providing the wiggle room you need to get the downpipe bracket off those threaded studs (Step 23) so you can pull the downpipes out the top.

Step 25: Remove the rear heat shield, yes. The rubber lining? I decided not to - it's glue (or melted?) to the engine bay, and I didn't want it flapping loosely after I reinstalled it. Also, I don't think it would have provided any extra room - I did struggle with a lack of space, but I did not find the rubber lining in the way.

Step 26: Sh*t gets real. Almost impossible to remove the stock downpipes because of their integral brackets (the brackets stick out and get caught as you're trying to pull out the downpipes). Best to remove the heat shielding that provides the channel through which the downpipes descend under the car (circled in red) - that should give you some extra room. I didn't have the right wrenches to access/remove the bolts holding on that heat shielding, so I struggled. That is to say, it's possible to get the downpipes out without doing this. But it was really tough.



Step 28: ARM sent me the clamps with the fasteners assembled backwards. Look at the red circles - the bottom is facing up (so to speak!). I had to pry apart the fasteners and assemble everything correctly so that I could access the bolt to tighten it (otherwise, the bolt face was pressed against the car).



Step 31: I don't have a JB4 and am trying the O2 sensor spacers from ARM. They don't come with instructions. They are two pieces (one straight, one elbow). I found that you have to screw in the straight piece to the new downpipes. Then, attach the elbow. Then, attach the O2 sensor (correct assembly circled in red, below). This is the only way the heat shielding fits over the spacers when you re-install it.



Step 34: I had a somewhat a tough time getting the ARM-supplied nut started on the driver side, but once done, you just tighten a little at a time, not past 20 ft-lbs. per the instructions. Since that tab on the downpipes is designed to contort its shape, I squeezed it onto the threaded stud with a pair of pliers just to allow me to get the nut started.

Step 35: No idea why this step is included - if I'm not mistaken, the brackets referenced here attached the stock downpipes to the back of the engine. But, they do not fit the ARM downpipes - that is, there is nowhere to attach the bracket to the ARM downpipes. I suppose I could have followed this step, but why? Just to attach a bracket to the back of the engine? Maybe I'm missing something here...

Step 36: Again, I think the order is such: splash guard (2), mid-under body panel (3), front under body panel (1).

Step 38: The top (pre-cat) O2 sensor locations in the ARM downpipes do not line up with the holes for the copper cups in the heat shield. Plus, once installed in the ARM downpipes, the O2 sensors are seated lower relative to the heat shield, and as such, it's not possible to re-use the copper cups. I'm a bit nervous that you can't reuse those cups - I'm sure they had their function - but they don't fit anymore.

[Jerfost]

Did you end up keeping the ARM downpipes on after a year now?

For the issues of exhaust smell, CEL delete pipes having to be dialed in to work, plus hitting the heat shield, PLUS my ARM downpipes did not slip on. They arrived as 3" and the factory midpipe was also about 3". Suck... so widened the midpipe, but would still not sit properly. Now trying to figure out do I push through on a custom exhaust transition/band or switch back to stock and save my sanity.

I'm a decent hobby mechanic and this was probably 9hrs over 3 days of going back and forth to make sure I wasn't missing steps... which I was, and the manual from ARM is crap like you mentioned above.

[BeGood69]

Originally Posted by Jerfost

Did you end up keeping the ARM downpipes on after a year now?

For the issues of exhaust smell, CEL delete pipes having to be dialed in to work, plus hitting the heat shield, PLUS my ARM downpipes did not slip on. They arrived as 3" and the factory midpipe was also about 3". Suck... so widened the midpipe, but would still not sit properly. Now trying to figure out do I push through on a custom exhaust transition/band or switch back to stock and save my sanity.

I'm a decent hobby mechanic and this was probably 9hrs over 3 days of going back and forth to make sure I wasn't missing steps... which I was, and the manual from ARM is crap like you mentioned above.

I just installed mine and i had the same issue fitting the oem exhaust. Also one of the cups did not fit right. So for now i just installed it 1/2 way fitting in after i tried to expand the oem exhaust..

[TuckerE36]

Was considering ARM DP's, they sound like HOT garbage, will be ordering VRSF i suppose lol

anyone every use RVG?

They look close to OEM

[Ben Richards]

Originally Posted by Jerfost

Did you end up keeping the ARM downpipes on after a year now?

For the issues of exhaust smell, CEL delete pipes having to be dialed in to work, plus hitting the heat shield, PLUS my ARM downpipes did not slip on. They arrived as 3" and the factory midpipe was also about 3". Suck... so widened the midpipe, but would still not sit properly. Now trying to figure out do I push through on a custom exhaust transition/band or switch back to stock and save my sanity.

I'm a decent hobby mechanic and this was probably 9hrs over 3 days of going back and forth to make sure I wasn't missing steps... which I was, and the manual from ARM is crap like you mentioned above.

Short answer - yes, they're still on the car.

Long answer - you are not alone. I worked on the install for more than a week during Christmas of 2020 (including ordering and installing the parts I broke by accident).

Earlier this year, I bought some AR Design catted DPs to replace the ARM DPs.

Problem (discovered just recently when I went to install them): the post-cat O2 sensor bung is located in a different place on the AR Design DPs than the OEM and ARM DPs. (https://f10.5post.com/forums/showthread.php?t=1887601).

Needless to say, they didn't fit. Time wasted this Christmas - three days.

I'm already in touch with my local shop to put the whole thing back to stock - or - I'm researching mod shops in the SE VA area and thinking about some kind of aftermarket, or custom, exhaust.

FWIW, the ARM DPs have really been pretty decent once I got them installed.

Good luck - if you have a minute, let me know what you decide to do.

BR

[Ben Richards]

Originally Posted by BeGood69

I just installed mine and i had the same issue fitting the oem exhaust. Also one of the cups did not fit right. So for now i just installed it 1/2 way fitting in after i tried to expand the oem exhaust..

Yeah, neither of the cups are currently installed on my car. Because there are no cats on the ARM DPs and the turbocharger-end of the DPs are therefore not as big around, the O2 sensors sit lower in the heat shield. As such, I found that I couldn't use the cups.

[Ben Richards]

Originally Posted by TuckerE36

Was considering ARM DP's, they sound like HOT garbage, will be ordering VRSF i suppose lol

anyone every use RVG?

They look close to OEM

The ARM DPs are not bad I don't think. I actually found they fit quite nicely (I had the slip-fit variety) once I got the OEM DPs out of the engine bay. On the other hand, ARM's CEL-delete package was garbage. I screwed around with those things and still got the CEL - every time.

If you're installing new DPs yourself, get ready, I think it's just destined to be a PITA.

I will say that ARM customer service was pretty responsive at the beginning. However, once I kept coming back with more questions, I think they got sick of me , and I stopped hearing from them. Had to figure out the rest by myself.

Honestly, for $400 or whatever it was, what did I expect?

BR