Exhaust design

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seattleswimboy

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I come from mustangs, M3's, and sport bikes and also have many friends with Harley's. The stock and aftermarket exhaust configurations seem to be lacking in any significant R&D for ideal flow and power output. With most true duels regardless of make or engine configuration, exhaust upgrades usually include one of or a combination of H pipe, Xpipe, stepped headers, or merge collector. The purpose of these features is to take advantage of the scavenging effect from one cylinder to the next helping create a suction action to pull exhaust gas out of the engine and help pull in air on the intake stroke. Even the R nine T stock comes with an H pipe header, but the R18 does not and I have yet to see an aftermarket company apply any of these features to their offerings. I can't understand these companies selling 2 or 3k full systems without providing any performance upgrade other then weight savings and removing the exhaust valve and cat. In it's stock form the r18 motor is significantly down on power compared to offerings from Indian and Harley, but with some actual R&D this engine could prove to be extremely capable. I would love to see the exhaust companies come out with some full systems that are designed to maximize power while still looking good, But in the mean time I will have to go the custom exhaust route just wished I had access to a dyno to do trial and error to find the best setup for this motor.
Anyone else find the aftermarket offerings lacking?
 
Nope. Sounds a bit like you’ve still got the Harley mindset that stock must be crap let’s do the Stage 1 thing. I’ve had Harleys myself and it is ingrained as soon as you buy one. BMW will have spent tens of millions in R&D with the best of everything to come up with the exhaust on our bikes. This is an understressed low revving twin where torque is king. If they wanted it to have 110bhp they probably could have got there but not without sacrificing some other characteristics. If it had 110bhp some folks would want 120bhp. Years ago exhausts were pretty basic and aftermarket slip ons could possibly release a bit of power (think Suzuki 1200 Bandit) but often they made things worse with flat spots, hard starting, just more noise.

Nowadays, with all the strict European regulations I can’t see that is still the case. Go look at say Akrapovic, a very respected aftermarket retailer, pick any bike and see the dyno charts before and after. It’s usually negligible gain overall with maybe 2-3 bhp at really high revs (if you even believe the charts anyway). I don’t think the gains are there to be had over stock, possibly a kg or two in weight, maybe a different look? Noise/sound is subjective and some prefer more volume, I get that but nowadays I prefer the more refined stock sound. I often ride past horses where I live now and a noisy bike would be a no no.

Harley have a massive aftermarket industry just waiting in the wings to take thousands more $/£ of us so possibly factor in some redundancy to the ‘stock’ bikes, to justify the expense and show some tangible results? Dunno🤷‍♂️. I‘ve had the Screaming Eagle catalogues myself with all the charts and puff piece ‘must buy’ propaganda. It’s very enticing and hard to resist.

If you do really go for it, get a full custom set up and aftermarket tune the CanBus system might then start playing up. Is it worth it? I don’t think the BMW brand and specifically the R18 is that sort of bike really. JMO and it’s no more valid than anyone else’s. I wish you well and hope it works out.
 
In my part of the world.... one seems to have one off two choices..... quiet and fast or slow and noisey..... my preferance is fast first.... so for my R18 quiet it is.... though quiet for me is no flapper and maybe some exhaust work.
 
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I've always felt that the DUCATI exhaust upgrade path leads in the exhaust industry; a TERMIGNOMI exhaust system would include the muffler system, an improved Air Box, Filter and a pre mapped ECU within a single kit.... and who doesn't love the sound of a DUCATI w/ a Termi system on it...
 
It looks like I may have found one system that has an H-pipe. The zard full system looks like it has one in the pictures but it's not very clear if it does or not. Can anyone confirm if the zard full system has an h-pipe connecting the 2 sides together?
 
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