I had never installed an accessory exhaust on any motorcycle before, so I wasn’t sure how involved it would be. But on the F800S, it couldn’t be easier. The instructions that come with the Two Brothers kit are pretty good, with color photos.
On the F800S, it’s a simple matter of removing the single bolt and disconnecting the clamp that holds the stock muffler to the exhaust pipe under the bike, just in front of the rear wheel. The stock muffler has an attached length of pipe to bridge the gap, but the M-2 exhaust has a separate connector pipe so that you can swap out the muffler when or if necessary.
Remove another bolt from the hangar in back of the passenger foot peg and the BMW muffler can be removed. Be careful though, it’s heavy!
Installing the Two Brothers M-2 is more or less a reverse of the procedure. The only instruction I didn’t follow was the guidance on mounting the Two Brothers V.A.L.E. (Variable Axis Locking Exhaust) adapter. This consists of two half-moon shaped pieces of aluminum that connect the exhaust can with the short adapter pipe.
According to the instructions, the V.A.L.E. pieces are supposed to be loosely mounted on the end of the M-2 exhaust first, then the adapter is supposed to fit over a flange on the short exhaust pipe adapter.
I could not get everything lined up by doing it this way, so I mounted the V.A.L.E. pieces after getting everything else loosely attached and aligned. I loosely fitted the short adapter pipe to the BMW exhaust manifold pipe using the clamp, then hung the M-2 using the supplied clamp that fits the BMW exhaust hangar bolt, then finally added the V.A.L.E. sections.
Get it all aligned as close as possible — be sure to look at the M-2 exhaust can from the rear of the bike to make sure it’s oriented correctly and then tighten all the bolts.
Here are some quick pics and an .mp3 sound file:
The Two Brothers M-2 carbon fiber exhaust looks good and sounds good. It appears that the only type of M-2 canister still available for the early F800-series is the 005-2530407V carbon fiber version I installed, which lists for $549.95. I found this one at “Fly-n-Cycle” on eBay for $395.96. They’re getting hard to find for the early F-series and I’m not sure if the fitment is the same for the new F800GT and F800R.
Power differences? Who knows. The dyno chart that came with the exhaust shows very little difference over stock and I say there’s no one who can really tell if the Two Brothers exhaust makes a difference. It’s all about the sound…
From “M.S.” (January 2015): “I just read an article about mufflers and saw that you used a real dB meter. I was wondering if you have a dB meter on your iPhone and if you ever compared the two. Thank you for all you do.”
Rick’s Reply: Actually, I’m an Android guy. I downloaded the Smart Tools Sound Meter v1.6 app from the Google Play store, it has a calibration feature. If I calibrate it to run close to the Extech meter, it’s fairly accurate but only with a steady (non-varying) sound.
If the sound is variable, like revving the bike, the app meter seems quite different than the Extech. So apparently with a steady sound, you can get them to read close but probably the tiny mic port on a cell phone limits the amount of variation. If it’s calibrated, the app sound meter should come close to correct for holding and recording max sound levels though.
From “S.M.” (January 2015): “As someone who has a F800GS, this review is of very close interest to me. I am thinking of getting one of the two brothers exhausts, mainly for the cost benefit and the weight savings.
The stock exhaust looks like a bazooka, and mine probably needs repacking after 3 years and 30k miles. I get 86db at idle, and 94 at 4k rpms on the stocker, using a free app on the phone. It’s not Harley loud, but something I don’t want to rock.
You don’t sound like someone from the loud pipes clan, and I feel your take is probably the most objective when it comes to Two Bros.
I’ve seen YouTube videos that say that the power tip does bring in the claimed db drop. You have a more professional gig to measure the sound output, I am looking forward to see how much the P1 improves – both in the measured drop and more importantly in the perceived drop. If I go Two Bros, my choice is the P1x tip, I very much like having a quiet exhaust.”