[burro_blasta]

Done a ton of searching but haven't found a DIY for our 535xi F10s. Would be great to hear from someone that's done this.

Everything I found is for rwd or 335s, which is close enough except it seems debatable whether you really have to lower the sub frame to get enough room to slide the DP in/out.

Also it seems like you can probably access the DP/turbo connection by taking off the passenger wheel and going through the wheel well, but I'm I haven't seen that confirmed for 535 x drives.

[Curtis001]

I just pulled and reinstalled my cat this past weekend. Not too difficult. You do need to pull the metal belly pan and the flexible cover behind it to access the cat. Undo the clamp bolt holding the cat to the mid pipe. Then you MUST remove the second o2 sensor to access the other bolts. Be prepared to scrape up your arm as it’s easiest to wedge your arm all the way up the passenger side to access the upper bracket mount. The other bolt and the cat to turbo clamp are fairly easy.

Once everything is unbolted, spray some WD40 onto the cat to mid pipe connection. Put some backwards pressure on the midpipe and wiggle the cat out of the midpipe. Not too difficult. Yes, it comes out easily without dropping the exhaust.

Obviously reinstallation of either the cat or a down pipe is simply the reverse. One trick that should make life easier, on the midpipe inlet, file the edge so it’s slightly rounded. It will make getting the cat or downpipe in a lot easier. Mine was sharp and made it tricky before I resorted to filing it.

Hope that helps.

Btw, unless you’re going to race it or hyper modding it, just gut the cat instead of buying a downpipe. Took me 5 minutes or less with a long spade drill bit and the inside cavity was left completely smooth and free flowing, and sounds friggin awesome with the M Performance Exhaust.

[burro_blasta]

Thanks, helps a ton. Good to hear you could slide it out without lowering the subframe at all. Wonder if that's an issue for 335s only.

On this part: "Be prepared to scrape up your arm as it’s easiest to wedge your arm all the way up the passenger side to access the upper bracket mount." - do you mean wedge your arm up the passenger side along the DP from underneath or through the passenger wheel well?

[JDMSteven]

I really really want to gut my cat but I'm afraid that if I want to reverse this a good OEM cat is so damn expensive! I feel like I'm better off buying a used cat and gutting it and keeping mine, since my car only has 40k on it.

[Curtis001]

First, yes, wedge your arm between the cat and the heat shield on the passenger side to reach the top bracket bolt. No need to remove the upper o2 sensor until the cat is out, and have it installed already when you reinstall the cat.

As for gutting the cat....once gutted, which was absurdly easy, the inside was smooth as a regular pipe. Just a larger cavity. I’m not racing my car, so I don’t care about the minimal increase one might gain using a same diameter pipe than the hollowed out cat. It also sounds amazing with the M Performance mufflers. I did have to add an o2 sensor spacer, and even with that I’m still getting a code on JB4 map 0, which is what’s needed to pass emissions. I’m in the process of getting the VSRF fix which I hope to have installed this weekend.

[burro_blasta]

Thanks!

[lsturbointeg]

there's yet a YouTube video specific our F10 535i DIY is there?

[burro_blasta]

Originally Posted by lsturbointeg

there's yet a YouTube video specific our F10 535i DIY is there?

No but there are a few write ups for F30 335s if you search the forums...more for RWDs than xdrives. I should be doing mine this weekend and will report back.

[lsturbointeg]

Originally Posted by burro_blasta

No but there are a few write ups for F30 335s if you search the forums...more for RWDs than xdrives. I should be doing mine this weekend and will report back.

take pictures if you could better yet create a DIY cause i'm sure it'll help out the members here

[Curtis001]

https://f10.5post.com/forums/showthread.php?t=1296547

This is what I used to do the job.

[burro_blasta]

Originally Posted by Curtis001

https://f10.5post.com/forums/showthread.php?t=1296547

This is what I used to do the job.

And you're xdrive, right? Was anything different than that DIY - bc that's on a RWD?

[Curtis001]

Yes, mine is XDrive. But I don’t think there’s any difference.

One thing I will mention though. You will need to remover the metal undercarriage cover, and the mid one behind it. It’s also not a 10 minute job to remove or reinstall. It took me a few hours to do, but then again I don’t work fast. Just take your time and make sure you don’t miss anything or forget to tighten anything in order, such as the brackets holding the cat in place BEFORE you reinstall the second o2 sensor. Also, if you have a flexible grabby thingy, that helped immensely with getting the o2 sensor connected back up top.

One other thing. I didn’t need to remove anything related to the intake to get access to and unplug the o2 sensors. Just removed the engine cover. That’s it.

[lsturbointeg]

lol I commented on that post!

[burro_blasta]

Originally Posted by Curtis001

One other thing. I didn’t need to remove anything related to the intake to get access to and unplug the o2 sensors. Just removed the engine cover. That’s it.

Thanks again, and good to know about the intake!