[franz_hermann]

Hey folks. I wanted to share my experience, some learnings, and some opinions on valvetronic's titanium catback exhaust for the g87. To start with some context, I obviously wanted more fun noises, but primarily I was looking to save some weight. I know there are a lot of people who will point out that 50 lbs saved on a ~3800 lb car is a drop in the bucket, but it was a factor for me when picking an aftermarket exhaust.

To that end, Valvetronic is unfortunately, in my opinion, really the only viable option for a full titanium catback on the market. There are cheaper options, but I opted for valvetronic because you're really paying for customer service/support over some of the alternatives. I also got a rec from my local independent BMW mechanic whose opinion counts for a lot to me. I say unfortunately, btw, not because I hate valvetronic or anything like that, I just wish there was more competition in the market so we had more choices.

Anyway, the exhaust showed up just a few business days after I ordered it. The packaging was done reasonably well, though there were a few minor scratches on some of the parts. Once I unpacked everything and confirmed I had all the parts I should have, I started the install.

One of the main motivations for writing this up is to share some details on how I did this in my own home w/a floor jack and jack stands. There are a lot of install vids on youtube but they're in professional shops and have more resources than a DIYer would have. What I will say is that, if you have a reasonable amount of experience working under a vehicle and feel you can do it safely, this install is absolutely possible to do at home and without a second pair of hands. The trickiest part is dropping the stock exhaust safely and without damaging anything, but I used a second floor jack to support the rear muffler and it was fairly easy (my primary floor jack stays in place as an added safety).

Anyway, after lifting the car (in spite of its appearance, you absolutely can lift the rear via the diff. The fins are very strong), I started undoing fasteners. BMW very kindly uses a bunch of 13mm fasteners on the cross brace and the exhaust hangers, so you don't need multiple sockets. The one caveat is that the hanger on the driver's side towards the front of the vehicle is an external torx for some reason. So make sure you have a set. One important note is that there are two fasteners which hold the sorta cross-over pipe at the very front of the stock exhaust. I didn't see them when I was undoing stuff so initially I had a lot of trouble getting the exhaust off. I got around this by first detaching the driver's side exhaust from the cross-over, and that actually made dropping the exhaust easier because the studs on both sides point the same direction. If you drop the exhaust including that cross-over pipe, the two downpipes sorta point away from each other and it could bind up.

Anyway, I dropped the stock exhaust by very slowly lowering the rear with a second floor jack I had, and I dropped it down onto a small dolly so I could roll the entire thing out from under the car (at this point, the front portion was already off the downpipes and I had the resonator propped up a bit on a piece of styrofoam). Once it was out from under the vehicle I started putting the new exhaust in.

Before you start putting the new pipes in, be sure to tighten all the weird abandoned pipes on the front-most part of the exhaust. There are two threaded caps and 4 plugged tubes that will rattle like crazy if they aren't good and tight. Accessing them after the install is a pain so make sure you do it before you put the exhaust in (ask me how I know this). I considered locktite-ing these but I wasn't sure if I'd need access to them in the future so for now they are just tight. If they end up coming loose I'll update this post to mention it.

Edit: Valvetronic confirmed that those of us w/o OPF should red loctite these bungs.

I started at the front, ensuring the first piece had a good connection @ the downpipes. The access to some of the fasteners, especially on the top is quite limited because of the shape of the first span of exhaust. Take your time and make sure you get it good and tight since an exhaust leak at the front of the car where everything is as hot as it's gonna be is bad news. I had to use a 13mm open-end for the hard-to-reach fasteners because none of my sockets could fit.

Next is the midpipe. As you add subsequent lengths of exhaust, it's a good idea not to tighten everything down too much so you can squeeze stuff together, but if things are too loose, they're gonna mate in the wrong position. So this is a bit of a balance act. After the midpipe, I actually went to the rear of the vehicle and hung the axleback assembly. My thought was that all the clamping and sleeving happens between the axleback and the midpipe, so if I get the two ends fixed in place in their home, it increases the odds that the other parts will sit in the right place. Once I had that done, I added the final two pieces that connect the midpipe to the axleback. This process was probably the most finicky part, but again, some patience and care will get you there.

Once I felt like everything was reasonably in place, I started to fully tighten everything down. Every so often I'd realize a sleeve or a pipe wasn't quite in the right place, so I'd need to loosen and readjust stuff. Again, take your time at this point. You're in the home stretch.

Once the exhaust was fully installed, I did my first start up. I had some leaks, so I went through and tightened everything again. Once I was happy with the connections, I started on the valve controller. This was very easy as there are some grommets that you can remove which lead directly into the battery tray in the trunk, and there's one on each side. I removed the green connectors from the valve looms, poked a hole in each grommet, and then slid the wire through. I then wound up the excess wire from each and then mounted the wire to the side of the battery tray with a zip tie + zip tie holder mount thingy. For power, I snipped the 12V plug off the end of the provided power cable (the g87 doesn't have a 12V receptacle in the trunk like the other G series cars have), and used a fuse-tap in the fuse box to steal power. As an aside, they do give you a fused power wire for this, but it’s not a proper fuse-tap and there are no unused connections in the fuse panel. This approach has the added bonus of being controlled by the BMS so the valve controller won't drain your battery. I removed some of the plastic rivets from the trunk liner so I could lift it up just enough to slide the conductor into the fuse box. I then used the ground on the fuel pump.

Finally, I used the garage opener built into the rear-view mirror to open and close the valves. Be aware: the remote they give you has three buttons on it, and the bottom two are the ones you use. The lower button closes them, and the middle button opens them. It's very confusing so make sure you're storing the right signal. It’s also surprisingly easy to press the wrong button while you’re programming, and if you store the wrong signal you have to clear all of your stored signals, which is very annoying.

Overall, the install was actually quite enjoyable and very doable as a DIYer. I'd say the bulk of the install took around 4ish hours, and then there was a somewhat disconnected tail of making little tweaks/cleaning up stuff (esp around the cable management) that totaled another hourish. The sound of the system is very satisfying. What I especially appreciate is that with the valves closed, your car sounds very similar to the stock exhaust with valves open. This means your neighbors won't absolutely despise you, but when you open the valves? Good golly the car sounds awesome. As an added bonus, the car actually sounds pretty good even in comfort mode, though you can’t really hear a difference if you open the valves.

If you're considering doing this mod and have questions, def feel free to ask and I'll share as much as I can.

[tgibrit]

thanks for posting, this on my to-do list