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The Anvil

Factory exhaust

9 posts in this topic

I have a 99 wr400. The thing runs great. It has the factory exhaust with the baffle removed. Some of the riding I do is in areas where I would like it to be alittle more quiet. If I locate a factory baffle and put it back in would I need to re jet it? Also is there any real performance to be had by leaving the baffle out?

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Yes, it will be quieter with the baffle in. And yes, there is performance to be had by having the baffle out. Not sure if you would have to re-jet or not. If you want ultimate performance, then yes, you would have to re-jet.

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Just look at the size opening of the baffle vs the open exhaust. Putting the baffle back in hugely restricts performance (and sound) and you will definitely need to rejet. In the stock form, the WR's are way down on available power in order to meet emission standards.

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Figure out how big your piston top is, the exhaust hole should be realtively the same size. I can bet you the piston is not the size of a mans pinky....

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You can run a PMB or GYTR aftermarket baffle (I have the GYTR, it was cheap), they keep you in the legal range of below 96dbl but don't restrict as much as the stock peashooter. My bike has plenty of kiddyup without being obnoxious.

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+1 on the GYTR baffle. It worked really well for me, for several years before I got the FMF Q slipon.

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+1 on the GYTR baffle. It worked really well for me, for several years before I got the FMF Q slipon.

Thinking of getting a FMF Q, mainly to lighten up the bike..

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I ran a ProMoto Billet insert on my YZ426 that I had put a WR muffler on. I ride a lot in Michigan and their rules on sound is 94dB. It ran fine and was quiet too. It is a whole lot cheaper than another exhaust

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