Easy 2 into 1 conversion?
Road Master
Joined: Feb 2021
Posts: 1,074
Likes: 475
From: Phoenix Arizona
stages
[QUOTE=Funnel;22161393]Not sure the factory pipe has changed, but like in the video, its minimally designed and without taking off one, theres dimples and bends that are as atrocious as that crossover extending into end of the pipe. I bought a Cobra Pro Chamber head pipe and side by side, the factory head pipe was something one can complain about. Its not much to make it as good as aftermarket.
I was looking to remove the catalytic converter. I paid good money for my bike, drilling it out is ridiculous IMO. If one cant afford proper parts, one shouldnt own the vehicle.
One comparison is old school muscle cars, factory cast iron exhaust manifolds, we put true headers on as a first modification after an air cleaner buy the proper full exhaust, 2 into 2 or 2 into 1, you will thank yourself later.
I did my 2017 107 in stages. What I could afford. I first added V&H HO slipons. Loved the better sound. BUTT dyno said it was faster... Next I de-catted the stock headpipe. I did the long way. NOT cut and weld. I took off and use various implements to get the cat out and then used a cylinder hone to smooth out and remaining pieces. BUTT dyno said even more power and faster. (proly not). Finally got the Cobro Pro Pipe, NO CAT, big cross over chamber, look almost like stock, full pipe under cross over. LOVE it.
I was looking to remove the catalytic converter. I paid good money for my bike, drilling it out is ridiculous IMO. If one cant afford proper parts, one shouldnt own the vehicle.
One comparison is old school muscle cars, factory cast iron exhaust manifolds, we put true headers on as a first modification after an air cleaner buy the proper full exhaust, 2 into 2 or 2 into 1, you will thank yourself later.
I did my 2017 107 in stages. What I could afford. I first added V&H HO slipons. Loved the better sound. BUTT dyno said it was faster... Next I de-catted the stock headpipe. I did the long way. NOT cut and weld. I took off and use various implements to get the cat out and then used a cylinder hone to smooth out and remaining pieces. BUTT dyno said even more power and faster. (proly not). Finally got the Cobro Pro Pipe, NO CAT, big cross over chamber, look almost like stock, full pipe under cross over. LOVE it.
Cruiser
Joined: Apr 2012
Posts: 194
Likes: 14
From: Florida
On the later M8 touring bikes, the crossover pipe to the left exhaust is fairly far to the back of the system, well after the catalytic converter. So head pipe performance shouldn't be any different. At idle, very little exhaust coming out the left pipe. At high revs? I don't know. Will the the stock right side muffler flow enough? Don't know. Will the plugging of the crossover cause a change in the reversion characteristics of the system? Don't know.
I might try just plugging up the end of the left pipe with something temporary, ride, and see what happens. I wouldn't mind losing the weight of the left pipe, and the change in appearance wouldn't bother me. If the stock muffler does't flow enough, then I could look at a new slip on pipe for the right side.
I might try just plugging up the end of the left pipe with something temporary, ride, and see what happens. I wouldn't mind losing the weight of the left pipe, and the change in appearance wouldn't bother me. If the stock muffler does't flow enough, then I could look at a new slip on pipe for the right side.
Cruiser
Joined: Oct 2025
Posts: 170
Likes: 70
From: US
Crossover
On the later M8 touring bikes, the crossover pipe to the left exhaust is fairly far to the back of the system, well after the catalytic converter. So head pipe performance shouldn't be any different. At idle, very little exhaust coming out the left pipe. At high revs? I don't know. Will the the stock right side muffler flow enough? Don't know. Will the plugging of the crossover cause a change in the reversion characteristics of the system? Don't know.
I might try just plugging up the end of the left pipe with something temporary, ride, and see what happens. I wouldn't mind losing the weight of the left pipe, and the change in appearance wouldn't bother me. If the stock muffler does't flow enough, then I could look at a new slip on pipe for the right side.
I might try just plugging up the end of the left pipe with something temporary, ride, and see what happens. I wouldn't mind losing the weight of the left pipe, and the change in appearance wouldn't bother me. If the stock muffler does't flow enough, then I could look at a new slip on pipe for the right side.
Cruiser
Joined: Apr 2012
Posts: 194
Likes: 14
From: Florida
I decided to do some testing. It turns out that a rag stuffed into the left exhaust pipe stops the flow. Doesn't come out at high output either. So it seems to be a good emulation of taking off the left pipe and plugging the pipe as described in the video, without the effort of actually doing the work. Went for a ride to see how it behaved. Butt dyno says:
1) at low speed, low load, no perceptible difference.
2) at freeway speeds, can maintain pace, but...
3) acceleration from say, 60 to 85-90 not as good. It just doesn't feel like it pulls as strongly and quickly.
So my tentative conclusion is that at low to moderate loads, the flow through a stock pipe is adequate, but at higher loads the stock pipe is a constraint. Maybe a higher performance slipon right side pipe would alleviate this problem? Don't know.
I noted in the video comments that DK Customs used "Tab performance bam sticks with louvered baffles" on their test bike. So probably a better flowing pipe than stock HD.
Anyway that's my experience, yours may differ of course.
1) at low speed, low load, no perceptible difference.
2) at freeway speeds, can maintain pace, but...
3) acceleration from say, 60 to 85-90 not as good. It just doesn't feel like it pulls as strongly and quickly.
So my tentative conclusion is that at low to moderate loads, the flow through a stock pipe is adequate, but at higher loads the stock pipe is a constraint. Maybe a higher performance slipon right side pipe would alleviate this problem? Don't know.
I noted in the video comments that DK Customs used "Tab performance bam sticks with louvered baffles" on their test bike. So probably a better flowing pipe than stock HD.
Anyway that's my experience, yours may differ of course.
Thread Starter
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Stellar HDF Member
Joined: Mar 2015
Posts: 2,948
Likes: 996
From: Winnipeg
If its in fact a true dual exhaust then there is no cross over! Hence the name.
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Stellar HDF Member
Joined: Mar 2015
Posts: 2,948
Likes: 996
From: Winnipeg
Upon contacting DK the rep said they tried tested the theory personally and found no change positive or negative in performance. Which begged the question why bother?
my question was born out of curiosity, so now I know and can move on.
my question was born out of curiosity, so now I know and can move on.
Cruiser
Joined: Jul 2022
Posts: 187
Likes: 107
From: galway ireland
I did it on my 107 dumped the LH silencer and made a cap for the cross pipe opening.
I also drilled out part of the baffle on the RH stock silencer.
Worked great IMO I dont think the LH pipe does a lot, the gasses have to make a 90 deg turn through that flattened crossover.
I also drilled out part of the baffle on the RH stock silencer.
Worked great IMO I dont think the LH pipe does a lot, the gasses have to make a 90 deg turn through that flattened crossover.
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