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So I need some clarification between a full exhaust and just cutting my OEM headers and adding the Mjs midpipe. So from what I've read, if I were to add headers I would see an increase in top end power (slightly) however I will loose a small amount of low to midrange power. Is this correct? I've also heard that the exhaust valve helps produce a little bit extra low end power. Is this also correct? I'm not really looking to add any top end power but if I can get a little bit more low to midrange power that would make me happy. That being the case, would the Mjs cat delete mid pipe yield best torque results? That way I can keep the exhaust flapper but get rid of the huge tumor (Cat) that my bike has lol or if there is another combination exhaust wise let me know. Additionally this would be paired with a pcv and a tune in time. Before anyone says anything about sprockets to increase low end power I know about changing them to "gain" low end power.


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i went with the mjs because of price honestly. i know you save a little more weight going full headers but i kept reading that they dont flow to much better than the stock ones. you can still gut the flap if you want and have a tuner fix the lower end. but yes it looks way better now haha
 

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There's not a lot of difference between the two. A good example for comparison was my bike & Buckley.S. I had the MJS cat delete with slip on & PCV, Steve at the time had a LV slip on, arrow headers & PCV. Both bikes were custom mapped on the same dyno by the same technician. Power and torque figures were pretty much the same.

 

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If you want low end neither are a good choice, leave it stock. The 09+ bikes had a much punchier low/mid range that made it (in my opinion) a better streetbikes than the 07/08 powerband. How low end are you talking, below 5,000rom?

Free flowing headers are good for top end power but at the expense of low end "grunt". Think of it this way: you have a pot with X amount of "power" marbles available you need to spread out in a line, that is your powerband. Thing is if you want to put more marbles on the top end you need to take them from somewhere else, where FI you grab them from? The low end.

I had an 01 CBR929RR that is still one if my favorite bikes of all time back in 02-04. At the time I bought what was the hot ticket exhaust, the Micron Serpent system, installed it, had it dyno tuned and hated it immediately even though it was a ~10hp increase in the top end. There was NOTHING below 5,000 rpm which made street riding frustrating to the point I pulled and went back to stock headers. MUCH better powerband. MUCH better bike experience.
 

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Discussion Starter #7
If you want low end neither are a good choice, leave it stock. The 09+ bikes had a much punchier low/mid range that made it (in my opinion) a better streetbikes than the 07/08 powerband. How low end are you talking, below 5,000rom?

Free flowing headers are good for top end power but at the expense of low end "grunt". Think of it this way: you have a pot with X amount of "power" marbles available you need to spread out in a line, that is your powerband. Thing is if you want to put more marbles on the top end you need to take them from somewhere else, where FI you grab them from? The low end.

I had an 01 CBR929RR that is still one if my favorite bikes of all time back in 02-04. At the time I bought what was the hot ticket exhaust, the Micron Serpent system, installed it, had it dyno tuned and hated it immediately even though it was a ~10hp increase in the top end. There was NOTHING below 5,000 rpm which made street riding frustrating to the point I pulled and went back to stock headers. MUCH better powerband. MUCH better bike experience.

That makes sense, thanks for the clarification. Just how much more "punchier" is the 09+ 600rr's?


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Discussion Starter #8
Thanks for all your help guys and clearing up my questions. I think Ima just leave the tumor on the bike ha. Sounds like I'll just loose low end power and that's not what I want.


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Thanks for all your help guys and clearing up my questions. I think Ima just leave the tumor on the bike ha. Sounds like I'll just loose low end power and that's not what I want.


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Honestly I didn't notice any drop in low end using the MJS cat delete. Remember, retaining the stock headers also means retaining the servo valve which will remain operational. This, together with the fact you aren't increasing the diameter of the headers means that the low end won't suffer horrifically.
 

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Honestly I didn't notice any drop in low end using the MJS cat delete. Remember, retaining the stock headers also means retaining the servo valve which will remain operational. This, together with the fact you aren't increasing the diameter of the headers means that the low end won't suffer horrifically.

Thanks Dkid. I've got some thinking to do now lol basically weather or not to do the cat delete.


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That makes sense, thanks for the clarification. Just how much more "punchier" is the 09+ 600rr's?


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I rode about 200 miles in Vegas on a rental blue 07 before I bought my 11. To me it was noticeable. Was it huge? No, but the power band on the 07/08 was more "linear" by pulling harder as the revs increased to a huge peak where the 09+ pull bumped at 4K or so, tapered very slightly around 7K and started pulling more linear from there up to 13K where it tapered off.

It's subtle but there; enough I didn't install the 08 ECU I had bought to put in my bike.

Honestly I didn't notice any drop in low end using the MJS cat delete. Remember, retaining the stock headers also means retaining the servo valve which will remain operational. This, together with the fact you aren't increasing the diameter of the headers means that the low end won't suffer horrifically.
That doesn't surprise me based on the power band of the 07/08 because there is not much low/mid to begin with. I think on an 09+ you might notice it more; I know on the larger bikes (929/954/1000RR) it was enough to be very annoying in my experience.
 

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I have the mjs pipe on mine. Honestly I never noticed a difference in torque at low rpms. All I know is I decreased some restriction in the exhaust which is somewhat beneficial whether it be gaining more top end and losing low end. But like I said, I didn't notice any difference. Regardless, it did shave some hefty pounds off the bike :)
 

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I have a Dan Moto Carbon GP exhaust + MJS Perf. mid-pipe/cate delete and I certainly feel like I did gain a SMALL bit of low end torque. Maybe its just my imagination though. Bike certainly sounds better (and louder). Less restriction - I'll take it! I have yet to get a Power Commander and get the bike tuned -- so far doesnt seem to be running lean or rich (doesnt backfire at all) but I will need to look into it.
 

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my opinion, just run a slip on.
if you want to run a full exhaust and currently have all stock exhaust, get a full yosh - best bang for the buck IMO
if you have a slip on and want full exhaust get arrow or MJS headers to get rid of the servo and the cat.

i have a akra slip on and wanted to get rid of the cat and servo so i got the arrow headers, amazing setup but ever since i got the slip on i wished i had gotten a full yosh.
thought about selling the akra slip on, even had it up for sale but it just wasnt worth it at that point. was cheaper to keep it and get the arrows.
 

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Wouldn't just changing the gearing to -1 in the front yield better down-low power by moving the ratios.

I run -1/+2 and have a lot more torque/acceleration due to change.
 

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Discussion Starter #17
Wouldn't just changing the gearing to -1 in the front yield better down-low power by moving the ratios.

I run -1/+2 and have a lot more torque/acceleration due to change.

Ya I could do that. But I do take it on the highway occasionally and don't want to be higher in the rpm's then I already am. I guess I could just do either a -1 in the front or just a +1 in the rear. Surly that won't jump my rpm's too much but still give me a little more acceleration.


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just get the mjs and call it a day
 

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I run -1/+2 and do about 30 minutes highway, and no issues. Sits about 7k on the tacho.
 
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