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Discussion Starter #1
Hi

I am going to weld in a wideband O2 sensor bung, and i was wondering to open up the exhaust and remove the SET valve and cat internals. BUT keeping the under the bike mufler, as I am not a fan of a to loud exhaust.

Does it make any sense? I figure the cat must make som back pressure? The SET valve will be disabled wia woolich software, so I figure i can dump it entirely.
 

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Hi



I am going to weld in a wideband O2 sensor bung, and i was wondering to open up the exhaust and remove the SET valve and cat internals. BUT keeping the under the bike mufler, as I am not a fan of a to loud exhaust.



Does it make any sense? I figure the cat must make som back pressure? The SET valve will be disabled wia woolich software, so I figure i can dump it entirely.


My understanding is that the cat Extends about an inch to the muffler box. It's funny, I want to more or less do the exact opposite you want to do. Was reading an article about the GSXR 1000... that thing has like two or threeset valves in it.... doubt they are all there for noise reduction


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Hi



I am going to weld in a wideband O2 sensor bung, and i was wondering to open up the exhaust and remove the SET valve and cat internals. BUT keeping the under the bike mufler, as I am not a fan of a to loud exhaust.



Does it make any sense? I figure the cat must make som back pressure? The SET valve will be disabled wia woolich software, so I figure i can dump it entirely.


I removed mine and it made a small difference to the sound , it doesn't have as much restriction as the muffler box as that thing has chambers the air has to go around and the cats straight through, if I had another bike the same I wouldn't even worry about doing it.
 

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Hi



I am going to weld in a wideband O2 sensor bung, and i was wondering to open up the exhaust and remove the SET valve and cat internals. BUT keeping the under the bike mufler, as I am not a fan of a to loud exhaust.



Does it make any sense? I figure the cat must make som back pressure? The SET valve will be disabled wia woolich software, so I figure i can dump it entirely.


 

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Discussion Starter #5
Thank you :) Will leave it in then.
 

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Changing the original exhaust manifolds by removing the valve and the catalyst does not make sense, especially if you do not want a noisy exhaust because the one that stops the sound is just the catalyst and a little bit the valve too. So in my opinion, or you get a set of aftermarket exhaust manifolds but you know they'll make a big noise or take a tube to modify your originals by removing the catalyst but keeping the exhaust valve.
 

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Discussion Starter #7
Changing the original exhaust manifolds by removing the valve and the catalyst does not make sense, especially if you do not want a noisy exhaust because the one that stops the sound is just the catalyst and a little bit the valve too. So in my opinion, or you get a set of aftermarket exhaust manifolds but you know they'll make a big noise or take a tube to modify your originals by removing the catalyst but keeping the exhaust valve.
Is this an assumption or something you know? I am quite sure the cat takes som noise, and also the SET valve (Under 4000rpm or so) But when you watch videos of modified headers, with SET valve and catalyst, but no mufler. They are noisy.

My bet is that at least 70% of the sound dampening is done in the mufler.
 

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When I had my woolich flash done the set valve was de-activated in the ecu so it is now in a permanent open state with the cables disconnected ( I will remove all the gubbins once i get chance ) the exhaust sound is definitely deeper and a bit louder ( the airbox baffle plate was also removed ). The cat is still in place and the stock can on the end, the tuner advised that if I go down the de-cat route then a stubby can would be a bit to loud / tiresome and to go for something a little longer just to tone it down a touch.
 

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Changed stock headers and cat for arrow headers. Went to a shop and welded the o2 sensor bung. Kept stock exhaust since changing it won’t give any extra performance but only weight savings.

Have a power commander with auto tune reading and updating the map on the fly.

Results. Bike is butter smooth. Tons of extra hp. Louder since the cat is the only thing keeping noise down.

Please let’s not get back into the myth that back pressure is needed!


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Changing the original exhaust manifolds by removing the valve and the catalyst does not make sense, especially if you do not want a noisy exhaust because the one that stops the sound is just the catalyst and a little bit the valve too. So in my opinion, or you get a set of aftermarket exhaust manifolds but you know they'll make a big noise or take a tube to modify your originals by removing the catalyst but keeping the exhaust valve.
Is this an assumption or something you know? I am quite sure the cat takes som noise, and also the SET valve (Under 4000rpm or so) But when you watch videos of modified headers, with SET valve and catalyst, but no mufler. They are noisy.

My bet is that at least 70% of the sound dampening is done in the mufler.
I do not say so much to say. The bulk of the noise is blocked by the catalyst and something even from the valve. The box below is a resonance chamber. According to me or make a change made well or better to leave. What you want to do is free a half-way exhaust manifold.
 

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Changed stock headers and cat for arrow headers. Went to a shop and welded the o2 sensor bung. Kept stock exhaust since changing it won’t give any extra performance but only weight savings.

Have a power commander with auto tune reading and updating the map on the fly.

Results. Bike is butter smooth. Tons of extra hp. Louder since the cat is the only thing keeping noise down.

Please let’s not get back into the myth that back pressure is needed!


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Back pressure is not needed but flow management is. the GSX-r1000 is sooo much louder it needs 3 valves to keep it quiet.....Or, maybe suzuki is telling the truth.
. Active exhaust management is a real thing.

The thing, GSX-S1000 is advertised as a street bike and the whole design is that of street bike, including gearing, exhaust, cogs,and fueling. Changing headers may have an affect but, one variable of the street bike formula has now been altered. So like any simple algebraic equation, changing one variable will change the result.

traditionally speaking, wide open exhaust benefits race/track bikes because wide open has more of an affect on higher rpms....this is a well established fact of exhaust building.....Gsx-s1000 is street bike. The principles of engineering a optimal bike for the street are different than building the optimal bike for a track.

Now having owned a fully tuned, with full exhaust 2016 and a stock engine 2018, the differences between the 2 were obvious and exactly consistent with what i described above. 2018 is faster off the line all the way up 2 about 8000rpm. Its at that surge of power around 8000rpm where the 2016 would show the power increase, but no contest before. 2016 was also butter smooth and tuned by one of the area's most recognized bike shops. (smoother than 2018 but 2018 is much better than 2016 when she was new)

The main reason I mention the above is because a lot of people dont want the characteristics of a track/race bike and what makes the GSX-s1000 so special is its street bike desgn. Its awesome you got your bike set up the way you like but people should know that they certainly risk losing something when they upgrade exhaust.

FWIW...I def prefer my 2018 on the road/street over my 2016.
 

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Discussion Starter #12
You have a point, but I have NEVER, seen a dyno that did not show a gain all the way, when fitted with a full exhaust.
 

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I know for a fact that the noise suppression is in the big (car) "pot" after the cat(pipe).
The cat do not muffle the sound much as I have tested that also with aftermarked cat insert (about the same size as stock cat).

The stock end can is basically an "aesthetic feature" with near to nothing "silencer" functionality.

I had the (expensive) Akrapovic end can with stock header/muffler/cat and it was *not* louder than stock end can.

With the Arrow headers the sound was deafening/fantastic depending on your "preferences" (sound-fetish). Stock or Akra end can.

As usual I do not recommend fiddling with the stock exhaust for other than if you're on budget :)

Edit:
I have seen many dyno sheets that shows nil to less hp/torque than stock with *legal* sound levels (db-killer in).
My BKing lost about 15HP with db-killer (but that is an extreme example). This was with Brocks system (terrible noise).
 

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I dont think valves are necessarily the ideal solution, just the best we can do with what we got. If I could borrow some tech from hollywood, my exhaust system would by built out of the same stuff the terminator was in T2. My exhaust diameter would be in constant flux and would be an adjustable parameter in woolich software.

If I were building my bike for the track alone...Nice fat tubing all the way back...straight as possible as I will be high RPM as much as possible (or else I'm losing the race.)

When is Tesla building us a 300 mile electric naked?
 

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delete cat

hello
this weekend I replaced the catalyst (2 pieces!) by a "dominator" pipe (which fits perfectly)
with the mufler, the noise is really too lood now
the valve remains and is necessary for torque on low revs I suppose
I am looking for a solution for less noise, anyone suggestions?
belgian biker
 

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hello
this weekend I replaced the catalyst (2 pieces!) by a "dominator" pipe (which fits perfectly)
with the mufler, the noise is really too lood now
the valve remains and is necessary for torque on low revs I suppose
I am looking for a solution for less noise, anyone suggestions?
belgian biker
Any pics of this. Are you using the standard rear section or a straight through type open pipe here?
 

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My full exhaust with a tune, improved power output in a notable way from around 3000 rpm up. Also doing a TRE. I can power wheely in first, no clutch, from 3000 rpm up. 6000 rpm up in second and third, and about 8500 rpm in fourth. I have reduced one front sprocket tooth as well, but I did that before the exhaust and tune if I remember correctly. The exhaust and tune made the largest difference to me. The TRE unleashed the beast too. I love the bike now for street riding! A 14” muffler makes it wail at WOT, but nice and mellow when just cruising. I feel like I have found the perfect balance for me. I will keep this bike forever I think. That is how much fun I have on it.
 
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