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Can i run the mjs and slip on without a tune safely? Also does the exhaust note get any deeper and burbly?
Yeah you can run it safely but it wouldn't be a bad idea to get a tune. Removing the cat and putting the mjs on will def make it louder. That's what I have on mine and it's pretty darn loud
 

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Tune

Yeah you can run it safely but it wouldn't be a bad idea to get a tune. Removing the cat and putting the mjs on will def make it louder. That's what I have on mine and it's pretty darn loud
When removing the cat and pairing the headers with a MJS cat-delete pipe and a slip-on you are converting it into a "fully open" exhaust. Will this affect how the bike perform and how the engine runs? Yes.

Will you see the full benefit from a doing this mod without having a tune? Most likely not.

Most people get a tune or a fuel controller (Power Commander, Bazzaz or similar) to account for this. You could risk running too lean mixture which is not good for your engine, nor fully utilize the potential of the modification.

When doing this mod I would also recommend to install block-off plates to reduce the popping on deceleration.

I have the MJS cat -delete pipe and a Akrapovic slip-on on my bike and it didn't make the bike much louder, but I guess i depends a bit on which slip-on you have.
 

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That’s actually what I want, make it louder and popping on decel, just not at the cost of my engine. Wanna make sure it’s safe without the tune. I just don’t want to spend 300-500 on a power commander, I’d rather spend that on new tires.
 

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That’s actually what I want, make it louder and popping on decel, just not at the cost of my engine. Wanna make sure it’s safe without the tune. I just don’t want to spend 300-500 on a power commander, I’d rather spend that on new tires.
If a decision on what part to buy is between new tires and a pipe to make the bike louder, i.e. not something actually needed, choose the tires first.
 

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I don't have any issues with cost.. so I went with a full system :laugh:.. Costs me a grip but the smile that it puts on my face whenever I twist that hrc throttle tube and hear that beautiful sounding full ARATA exhaust.. priceless.. I'd say whatever makes you happy just get it cuz in the end you will be the one paying for whatever it is.. Oh and yeah, you will need a pcv or bazzaz or something for that MJS pipe or full system or else you'll lean out.






 

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CBRCHRIS
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the HESV servo valve is for noise emission purposes only its a DB noise reducer, it only fully opens between 6000k and 9000k RPM you can tell when you have a slip on installed and your mufflers loudest point is between 6k and 9k rpm. this valve mostly closes at high rpm to keep the DB's down but it hurts the power and causes vibrations. alot of people say the 07-08 cbrs had more power stock and the reason is after 2008 the servo valve and cats were installed hindering the HP and adding more weight. removing this valve reduces vibration and increases flow. back when i first got my bike this was the first thing i did tied the valve open and removed servo motor and added a servo buddy the bike ran smoother and night and day difference with mid rang and top end. four stroke engines operate better the faster you can get air/fuel in and exhaust out. Again the HESV servo valve has nothing to do with back pressure what do people think its a 2 stroke lol.
 

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CBRCHRIS
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if you were to do a cat delete and servo delete basically making your stock headers with no restrictions youll see the same power results on a dyno, the main benefit of aftermarket headers for example mine i used arrow racing titanium headers is weight reduction. my stock headers vs my arrow racing was a huge difference. the aftermarkets have slightly wider piping but that make no difference unless you have internal engine work. remember weight to HP ratio is amazing alot of people dont realize how much faster you can be by droping 40LBS off the bike.
 

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the HESV servo valve is for noise emission purposes only its a DB noise reducer, it only fully opens between 6000k and 9000k RPM you can tell when you have a slip on installed and your mufflers loudest point is between 6k and 9k rpm. this valve mostly closes at high rpm to keep the DB's down but it hurts the power and causes vibrations. alot of people say the 07-08 cbrs had more power stock and the reason is after 2008 the servo valve and cats were installed hindering the HP and adding more weight. removing this valve reduces vibration and increases flow. back when i first got my bike this was the first thing i did tied the valve open and removed servo motor and added a servo buddy the bike ran smoother and night and day difference with mid rang and top end. four stroke engines operate better the faster you can get air/fuel in and exhaust out. Again the HESV servo valve has nothing to do with back pressure what do people think its a 2 stroke lol.
Um 2007 CBR fiche.

Servo motor:

https://www.bikebandit.com/oem-parts/2007-honda-cbr600rr/o/m15636#sch420813

Headers. You can clearly see the cat:

https://www.bikebandit.com/oem-parts/2007-honda-cbr600rr/o/m15636#sch419520

I think your understanding of the 07/08 vs the 09+ is incorrect.
 

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CBRCHRIS
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Correct my comment about the servo is correct I miss typed the years I was referring to meaning older bikes the 2008 only had ecm program differences like fuel and timing giving the increase in HP I was referring to older models not 08-16 my bad on the miss information. But the servo information is correct.
 

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Mine just got louder, almost sort of “buffets and drones” now. (If that description makes any sense)
Pissisng the CO2 sensor and installing the lambda bridge worked a charm, no more nose dive on slight throttle reduction
More power? Meh don’t think so, less maybe. Definitely flatter curve though.
 

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ok, so I did this a couple of months ago.

Heat on my right heel?? Night and day difference. Was horrible, enough that I often had to ride with my foot off the peg, or with my heel on the peg and my toe facing outwards. Now, I can ride it as normal.

power? I didn't dyno it before and after, so I can't say for sure. And I haven't even had it over 11.5k yet. However, it seems to have slightly (but noticeably) brisker throttle response. Quite nice in my opinion. I know for certain that it didn't hurt power or torque.

Fuel economy? It has helped with this as well, if only a small amount. I can go 300km on a tank. Done it several times. Mixed driving types.

sound? Its a little louder, and a bit more "crisp" a bit more "snarly" nothing world changing, but a little bit.

The downside I find is that you can clearly smell exhaust now. Not just when cold, but all the time, when stopped, or if following the bike. Not horrible, but definitely something.

the fit is good, and it looks ok. Not amazing, but decent. However, the inside of the pipe shows a bit less attention. And yes, you won't see in there, but the exhaust has to flow in there. I don't have any pictures of it, but suffice it to say that it took me about 2 hours of grinding on the welds, and the excess metal. I have some fabrication experience, and decent professional tools, so I was able to do this. I don't have a flow bench to say how much was gained, but one of the joints was pretty poor tbh.

For the price I can't really complain, but I would like the inner surface to be smoother in something high performance. I've built many high performance cars and this pipe wouldn't be received with high praise.
 

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Firstly, thanks to all the replies on this thread because that did answer all the questions I had on my mind. However, I had one more question. I was considering ceramic paint on my exhaust. There are other threads where I could ask this question but wanted to have all answers in one thread so that all information regarding exhaust mod will be in 1 thread.

The questions is, Can I paint only the mid section all the way up to the slip-on? Has anyone done that? The reason I was thinking of that was because, in one of the threads I read that painting the header will over heat the engine. What I was logically thinking was that the air gets colder half way through and by ceramic coating the second half of the exhaust, the heat will be retained until it exits the slip-on, which technically should improve the exhaustion of gases. Also, the thought is that, the ceramic coating will reduce the exhaust smell (due to over heating) that people talked about, after deleting the CAT.

Please help me with information or reference to good posts/articles. Any help is appreciated.
 

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Tune

...I have the MJS cat -delete pipe and a Akrapovic slip-on on my bike and it didn't make the bike much louder, but I guess i depends a bit on which slip-on you have.
Similar experience with my setup. While it’s well known the Akrapovic is one of the more “tame” exhausts to begin with, the MJS did add some more depth to it while still retaining the “smoothness” of the Akra sound.

 

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I just recently deleted my whole exhaust valve setup. Yes, the whole thing. I pulled the header off, cut off the bracket, cut the bolts holding the valve on the throttle shaft, cut the shaft out and welded short wide screws in the shaft holes. Its just a header now, fitting into the MJS pipe, and the stock muffler. I cleaned up many of the welds on the stock header while it was off, mostly for aesthetics, but I'm just funny that way. I also removed the cables and servo motor, and put in a Servo Buddy.

Bike is a tad louder, but not much. it just sounds like a 600 supersport bike should sound. not choked off, just freer sounding.

it revs out much easier on top. it IS something you can feel. Just more eager overall. more willing to try to hit redline.

I also ride it a lot in town, just riding, not ripping on it, so I know how it felt before at low rpm. I have to say nothing is lost at low rpm either. I regularly roll along at city speeds in 4th and 5th and low rpm. Its still just as crisp and smooth as stock, if not better. It will pull smoothly from 50km/hr in 4th and 5th, even up fairly steep hills. Id compare it to a modern Japanese V6 in a smaller midsize sedan.
 
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