[Brett530]

I installed a CG DS-1 Downpipe over the weekend and wanted to pass along my learning as a downpipe beginner. I have not done any downpipe or exhaust work in the past so I was going slow just focusing on one step at a time. My install has several differences from what I have seen on this forum. These tips apply to a RWD F30 340. There are probably differences for xDrive.

Summary:
- I used ramps (no lift)
- No removal of bottom engine tray/cover
- No Disconnecting O2 sensor wires
- 2.5 hours going pretty slow - if I had to do it again, it would probably take 1 hour.

I did not do photos, which I know makes this really boring. Please consider this a supplement to the DIY from F30MGM. https://f30.bimmerpost.com/forums/sh....php?t=1428608
He did a great write up with photos which helped me a lot. I'm just sharing some of the details that slowed me down when I wasn't sure what I was doing.

1. Ramps: I have standard plastic Rhino ramps that I extended with about 3 feet of 2x10 lumber to allow a gradual slope. I drilled a hole through both to drop in a long bolt (lag screw) to keep the wood from sliding on the ramp. They work great and getting the ramps in the perfect position is the only hard part. It helps to have a spotter to tell you if you are staying aligned. I used a wireless security camera and my phone to watch, when I had to do it alone.

2. Heat: I could have put the car on ramps the night before to allow enough cool-down time, but instead I started the car backed out of the garage and turned it off. I positioned the ramps and then drove up. With probably less than a minute of engine time, the pipe was a little too warm, so I let it sit for about 30 minutes.

3. Air Box: Unscrew the airbox clamp and slide it down. Unclip the lid and remove it. Remove the filter. The air box is held in by 3 rubber mounts. It is not fastened to the rectangular intake pipe. I was worried I might break something. It just pulls up with some force. 2 of the rubber mounts came up with the air box, so I had to pull them off and remount them at the end of the job before putting the box back in.

4. O2 Sensors: Pull off the engine top cover. I was not exactly sure how to get the O2 connectors apart. I damaged the first one and decided to change strategies. I loosened the O2 sensor and since it only needs a few rotations to come off, I just twisted the wire as I unscrewed it with the wire connector still attached. At first I didn't think it would work, but when I made sure the wire twists were evenly distributed along the entire length of the wire and not stressing the wires right at the top of the sensor, it worked just fine with no risk of damage. The lower/back sensor is even easier since it has a longer wire to distribute the twists. If you use this method, pay attention to the number of rotations, so that when you reinstall the sensor, you can make sure to pre-rotate the wires so that you are untwisting the wires as you tighten the O2 sensor.

5. V-Clamp: The clamp that holds the downpipe at the top has a bolt and nut at the bottom that hold it tight. The nut will not rotate since it is boxed in by the clamp. Once you get the nut loosened enough it will push past the part holding it. Keep your hand on the nut so it doesn't fall ('cuz then you might have to remove the bottom cover to retrieve it). The v-clamp seemed like it was welded in place, so I wasn't sure what to do. It was just stuck and came loose later. I left the clamp on and went to work on the other two places that hold the pipe.

6. Mid-Pipe Clamp: At this point, it was time to get under the car. One downside of ramps is that it would have been nice to get under the car from the side just behind the passenger-side front wheel. That is where the downpipe connects to the mid pipe. The lower engine cover does not obstruct this area, so I chose to leave it on. I did the whole job without removing it. Unscrew the clamp and unscrew the midpipe hanger bracket nut just a few inches further back. I could not figure out how to separate the downpipe from the midpipe. Under the car I could not get any leverage. I used a dead-blow (shot filled) hammer and hit the midpipe bracket to push it toward the rear off the downpipe. It took about 30 hits but it separated. After that I removed the two hanger bracket nuts, and worked the v-clamp off.

7. Pipe removal: I'm pretty sure there is not enough clearance to remove the pipe from the top. With a little twisting it came out the bottom. It was a little tight since there is not much clearance between the ground and the bottom of the car, but I was able to flex the stock downpipe at the braided section enough to get it out.

8. Install: The removal is the hard part. I carefully removed the old gasket with a sharp pry tool. My car only has 11k miles, so removal was not a problem. It slid out pretty easily and into the new pipe easily. I slid the pipe up from the bottom and got it close to the right position. I then went back to the top and loosely fastened one of the pipe hanger bracket nuts. Then back under the car to connect the downpipe and midpipe. I put a little hi-temp anti-seize on it just to help it slide into place and make sure separating them in the future wouldn't be a problem. It probably isn't necessary. The DS-1 pipe fit perfectly and I did not have to expand the end. I connected the top end loosely with the v-clamp in place and tightened the the 2 hanger bracket nuts. Then the v-clamp and then the mid-pip clamp and nut for the midpipe hanger bracket. Put the O2 sensors back on, then airbox, etc.

Good luck!

[E90ROXS]

Thanks for the DIY.

[mike@x-ph.com]

Thank you for sharing

[wskhan]

Currently installing VRSF catless downpipe. I was able to disconnect it from the midpipe but can't figure out how to get it loose from the turbo. Any suggestions??

[drivef30]

Originally Posted by wskhan

Currently installing VRSF catless downpipe. I was able to disconnect it from the midpipe but can't figure out how to get it loose from the turbo. Any suggestions??

There is a 13mm bolt that hold the DP to the turbo... the bolt is located towards the ground looking from the top of the engine bay.... you need to remove the airbox to get access to it. After loosening the bolt, you just pry the vband open and youll be able to remove it then.

[wskhan]

Originally Posted by drivef30

There is a 13mm bolt that hold the DP to the turbo... the bolt is located towards the ground looking from the top of the engine bay.... you need to remove the airbox to get access to it. After loosening the bolt, you just pry the vband open and youll be able to remove it then.

Appreciate the help. Was able to get downpipe installed. Have only driven it a few miles. Great improvement
However noticed that downpipe is making contact with metal under tray. I will probably have to readjust it

[Ahanix]

Just wanted to say thanks for this supplemental guide and also to add a couple notes for anyone doing this install.

1- Save yourself a lot of time and get a T50 torx and unbolt the exhaust bracket towards the back of the car. This will give you more leverage to get the downpipe out and back in the car. I could have saved myself at least 45 mins of my 2 hour install just from this.

2- When you disconnect the exhaust clamp from the midpipe, if it’s not moving after you unscrew it 99% of the way, smack the clamp with a hammer so the clamp is loose, this should make the pipe loose enough for you to wiggle it out.

3- If you are installing this solo like I did, when you get the DS-1 back up in the engine bay, you can hang it on one of the bracket bolts so you can go back to the top of the car to finish the install.

[00e1]

Thank you for this! Currently in-process and the tips help a ton!

[BornATeste]

Is there any interest in a used CG DS-1? I have one that i'm on the fence about swapping out for a catless VRSF.

[Ahanix]

Originally Posted by BornATeste

Is there any interest in a used CG DS-1? I have one that i'm on the fence about swapping out for a catless VRSF.

Any reason you're looking to switch?

[BornATeste]

Originally Posted by Ahanix

Any reason you're looking to switch?

I want my car to be as loud as possible without swapping my catback. i already have the Akrapovic system. Also interested if there is a seat of the pants difference from removing the restriction of the cat.

[AleksanderSuave]

When you get the downpipe fitted roughly in place, get the bottom inside the midpipe, and then tighten the midpipe hanger (not the downipe to midpipe clamp bolt).

Having the midpipe pushing up on the downpipe will help hold it in proper spot for the turbo, so you can tighten the clamp.

For the O2 sensor connectors, it was easy once I figured out the first one. Pull the gray tab, then press it down, then apply pressure on the lip in what looks like the middle area, towards the tab, and it slides right out.

when you're down there underneath the car, is a good time to check if your midpipe clamp bolt and nut setup needs replacing. my car is a 2017 m240 and the midpipe clamp bolt was rusted beyond repair. had to dremel it out. A replacement carriage bolt, 2 inch length, I believe 5/64" size, and 2 nuts, in stainless steel, will cost about $2.44 at HD, and do the trick.

Also, you can do a majority of the work with one ratchet, including the O2 sensors and the mounting bolts for the DP, get a swivel head, like this tekton 3/8 https://www.google.com/search?q=tekt...hrome&ie=UTF-8 shallow and deep socket will cover most of the bolts, and a crowfoot and 3" extension will take care of the O2 sensors.

anti-seize on the O2 sensors when you re-install, incase you ever have to do this again.

[Asvplee]

+1 on anti seize on o2 sensors for easy removal in the future. Also depending on mileage before downpipe removal Get a new turbo to downpipe gasket.

Mines was still in pretty good shape (29k miles) before I put in my down pipe so I reused but if i read up on the forums beforehand i would’ve replaced.

Good to replace o2 sensors also while downpipe is out.

[JustDave]

Originally Posted by BornATeste

Is there any interest in a used CG DS-1? I have one that i'm on the fence about swapping out for a catless VRSF.

Let me know how much. My lease is up in a few months, doing some test driving on Monday. Not sure how I feel about the M340, giving the X3M a drive. But 340’s are going pretty cheap and I like mine, so I’m considering buying it out, making it faster and being financially responsible.

[BornATeste]

Originally Posted by JustDave

Let me know how much. My lease is up in a few months, doing some test driving on Monday. Not sure how I feel about the M340, giving the X3M a drive. But 340’s are going pretty cheap and I like mine, so I’m considering buying it out, making it faster and being financially responsible.

I'm really only open to swapping it for the right price. I'd do $800 shipped. I'm curious what is the buyout for your car? Is it m-sport? What year and miles? I ask cuz I'm looking to get rid of mine and get a truck. Trying to see if it's worth it based on how much I still owe on it.