Exhaust Systems

MilwDave said:
I question the need to gut that cats to get better sound. I’ve seen numerous videos of slip-ons used on bikes in Europe that have great sound. The bike builders there take the Euro regulations seriously and leave the cats intact.
Click to expand...
PREAMBLE

The fishtails are tricky. The straight pipes are a no brainer. My comments and the following is all related to keeping the fishtails. My personal belief is that it is not worth spending money to buy new straight pipes to make them louder. If that’s what you want just deal with the baffles (drilll) discussed other places. I am specifically commenting on the challenging fixes with the fishtails. Possibly my previous comments are confusing In that regard.


EXHAUST COMMENTS

Fishtails. It is good to question the cat removal in general. I dont think you need to do it if you can do other things. Easier said than done. Based on my experience with ‘my’ evolution of sound on the r18 exhaust mods, the fishtail mufflers do a magnificent job at their job; too good. By replacing them you can get all the sound you want. Almost anything is louder if that is what you are after. But to modify them you must remove some of the guts to make them not muffle so well. (Likely what the guy in Europe is doing idk) I don’t know how to do that with the tools I have.

Thus, I have gone the route of doing what I can: Drilled out the baffles, opened the flappers and removed the cats. Perfect sound due to the cumulative effect of many small changes. (Side note when tuned it is darn engaging to ride)

The baffles seem pretty minimal when you look at them. not sure what drilling them did for sound but it had to speed the exhaust up. So performance boost as well.

The flappers open under hard acceleration anyway, so that fix is best for low throttle input sound. Likely only performance gain is getting rid of the hp and torque dip when they open. (See graphs, Brentune claims they solve this, but I think it just involves just having the baffles open all the time) . That opinion is based on what I have read on other bmw forums regarding the baffles. I am not that smart to really know.

The cat removal clearly does sound better. It also greatly speeds up flow so performance is increased and increases the sound. I would likely not do it on non fishtails.

Bottom line for me. Fishtails take work to sound better. Either (partially) gut them or do other mods to the system. I changed airbox, removed the cat, opened the flappers and drilled the baffles. Could not be happier. YMMV FOR SURE.
 
Last edited:
R18C said:
First thing to consider,$1600 each muffler to replace once you have gone down that road.
Next,There is 1 guy I heard of that drilled the mufflers and we are still waiting for a sound clip.Noise is relative and subjective.If you don't like it what is your next step in your plan.
The Bren Tune and DNA filter will give you some more grunt and sound.
Last thing,I have a Indian 116 BBK build w/headwork and many performance parts.I decieded to take off the Rinehart mufflers and try the stock oem mufflers just to see how it sounds and performs.It actually sounds nice and barks pretty good.I picked up tq on the initial 1/4 throttle/low end.
Mufflers are overrated to be sure.
If you can wait and find a set of take offs to cutup or buy a set of aftermarket mufflers.After having a loud bike the BMW is really nice with the Tune,aircleaner and black RSD end caps.Nice rumble and I did'nt destroy a pair of $3200 mufflers.
I always keep a pair of sock oem unmodified mufflers and header.

btw,there is also a unit to electronically keep the flapper valves open that will give you more volume.These work on the R18: 42-2757



https://www.amazon.com/Woodcraft-Se...7e-9dcf-fc0b8e81d215&pd_rd_i=B07F8G6L1X&psc=1

[/URL]
Click to expand...
Did you have the stock fishtails? What exhaust did you add the end caps to?
 
Gr8adv said:
PREAMBLE

The fishtails are tricky. The straight pipes are a no brainer. My comments and the following is all related to keeping the fishtails. My personal belief is that it is not worth spending money to buy new straight pipes to make them louder. If that’s what you want just deal with the baffles (drilll) discussed other places. I am specifically commenting on the challenging fixes with the fishtails. Possibly my previous comments are confusing In that regard.


EXHAUST COMMENTS

Fishtails. It is good to question the cat removal in general. I dont think you need to do it if you can do other things. Easier said than done. Based on my experience with ‘my’ evolution of sound on the r18 exhaust mods, the fishtail mufflers do a magnificent job at their job; too good. By replacing them you can get all the sound you want. Almost anything is louder if that is what you are after. But to modify them you must remove some of the guts to make them not muffle so well. (Likely what the guy in Europe is doing idk) I don’t know how to do that with the tools I have.

Thus, I have gone the route of doing what I can: Drilled out the baffles, opened the flappers and removed the cats. Perfect sound due to the cumulative effect of many small changes. (Side note when tuned it is darn engaging to ride)

The baffles seem pretty minimal when you look at them. not sure what drilling them did for sound but it had to speed the exhaust up. So performance boost as well.

The flappers open under hard acceleration anyway, so that fix is best for low throttle input sound. Likely only performance gain is getting rid of the hp and torque dip when they open. (See graphs, Brentune claims they solve this, but I think it just involves just having the baffles open all the time) . That opinion is based on what I have read on other bmw forums regarding the baffles. I am not that smart to really know.

The cat removal clearly does sound better. It also greatly speeds up flow so performance is increased and increases the sound. I would likely not do it on non fishtails.

Bottom line for me. Fishtails take work to sound better. Either (partially) gut them or do other mods to the system. I changed airbox, removed the cat, opened the flappers and drilled the baffles. Could not be happier. YMMV FOR SURE.
Click to expand...
Your comment is the best I found outlining how to cicumvent Fishtail Surgery!
I would love to know where exactly did you drill? Any tips on cat removal? What was the airbox replacement? I need someone to walk me through some of those 🤷🏻‍♂️
 
theMucker said:
There are so many riders and customizers bent on changing the R18 exhausts system, I hope that someone will remove the stock mufflers and not want to keep them in storage. I have some ideas to modify them that will require a pair of donor mufflers. The result may end up as junk in the dumpster, if it doesn't work out. But only a pair of OEM mufflers to experiment with will tell the tale. If anyone has a pair in good condition that is just going to collect dust, please let me know.
Regards!
Click to expand...
Hello, I have a pair of mint Classic mufflers
 
You must log in or register to reply here.
Back
Top