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Are Stock 2013 Silencers Restrictive

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A friend of mine took the muffler apart on his 2013 450sxf and found that one of the cores which the exhaust gases goes though is no bigger then a finger .

If this restricts the enging breathing , can you remove this core and would it increase power ?

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A friend of mine took the muffler apart on his 2013 450sxf and found that one of the cores which the exhaust gases goes though is no bigger then a finger .

If this restricts the enging breathing , can you remove this core and would it increase power ?

Yes. The baffle really restricts the low end power. Either remove it, or buy someone's 2011-2012 silencer from a 250/350.

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Dyno tests on the 250f and 350f show no gains and some losses from most aftermarket pipes, only a full fmf with power bomb and remap showed less than 1 HP more, my STD 13 250f with mapping produced 40.7hp a 14 with full pipe and map made 41.5hp, mine has 26hours on the clock

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Dyno tests on the 250f and 350f show no gains and some losses from most aftermarket pipes, only a full fmf with power bomb and remap showed less than 1 HP more, my STD 13 250f with mapping produced 40.7hp a 14 with full pipe and map made 41.5hp, mine has 26hours on the clock

 

Thanks mog thats all i needed to know ...

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Dyno tests on the 250f and 350f show no gains and some losses from most aftermarket pipes, only a full fmf with power bomb and remap showed less than 1 HP more, my STD 13 250f with mapping produced 40.7hp a 14 with full pipe and map made 41.5hp, mine has 26hours on the clock

Exactly.

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So are we saying that there is a difference with the 450sx?  I can tell you that putting a full exhaust on these bikes makes a real difference.... it was highly noticeable with added low end grunt and increased rev snappiness through the entire throttle.

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So are we saying that there is a difference with the 450sx?  I can tell you that putting a full exhaust on these bikes makes a real difference.... it was highly noticeable with added low end grunt and increased rev snappiness through the entire throttle.

Well, the dyno curve is slightly different, so you will feel that. However, in terms of power output, it doesn't change.

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So you are saying that Motorcross Action Magazine, Pro Circuit research (all the French guys I talked with that build these exhausts and fuel maps), Transworld Motorcycle, and Motorcycle USA are all wrong?  Independent dyno results show these bikes can put over 60HP out with some of these full exhaust systems.  I'm not hating on your info, I just would like a little rebuttal over the ample research I did before spending $800 on a full system.

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So you are saying that Motorcross Action Magazine, Pro Circuit research (all the French guys I talked with that build these exhausts and fuel maps), Transworld Motorcycle, and Motorcycle USA are all wrong?  Independent dyno results show these bikes can put over 60HP out with some of these full exhaust systems.  I'm not hating on your info, I just would like a little rebuttal over the ample research I did before spending $800 on a full system.

So here's the scoop as it pertains to a modern KTM 4 stroke. The silencer and midpipe, stock vs aftermarket, are similar diameter pipe because they need restriction to help build back pressure, which in tern delivers better mid-range. The silencer itself, does have baffles in it, which is why the stock system passes the strict european decibel test. Yes, if you buy an exhaust which doesn't have baffles, which doesn't pass sound regulations AND you purchase the KTM programmer, which allows you to upload a map... Sure, you could probably see some actual gains of 2 - 3hp at the absolute top of the RPM curve. But you will loose mid range because the back pressure is important.

I have an akrapovic exhaust on my 250SXF and it makes zero difference in the performance of the machine. There was no reason to buy it outside of the sticker I could have bought and put on my stock exhaust. ;)

Edited by tye1138
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I have no data on the 450 only the 250 and 350

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