Noise reduction

In the UK a lot of tracks are getting very strict on noise levels. Many practice tracks will not let you on if you are not running an enduro or Q pipe.

I have a yz426 which runs a ProCircuit system. This will never pass any noise tests. With this in mind I have just got hold of a WR system from e-bay. I have also got a stock header and Arrow Silencer. I might run with the Arrow silencer and stock header and when I fail a test I will stick on the WR silencer.

I have a couple of questions I hope somebody can help with....

What is the db rating for the WR pipe with and without the insert?

How bad will it make the bike run? I'm not concerned about overall power as it has more than I can handle.


The DB rating on the stock WR exhaust is very quiet (probably < 92 DB) but you will hate the power vs your system especially off the bottom. I would look at the FMF Q since it's much better than the stock hardware.

I have a 98 wr400 / stock pipe with a pro moto billet insert , makes legal sound and the power is good .Good low end but it does hurt the top end a little . :cry:

I have a stock WR with a Quietproducts insert. It replaces the pinky size insert with a 1 1/2" diameter baffle. It has passed several sound tests at 94-95db. My stocker without the core reads 99-100db. It sounds throaty, but takes the bite out. Not sure if you can get one in UK though. Might want to email 'em. The site is

Any body know what level the Procircuit Ti 4 silencer produces?

A friend of ours got tested at hollister a week or so a go with a FMF power core on his WR 400 they shut the meter off at 106db and gave him a fix it ticket he had a month to fix it.

I installed the WB E2 slip on. It has the race insert or you can put in the cork. Should take me down to 96db. Ridding in randsburg this weekend guess I'll find out if I pass the test. The insert doesn't rob to much power from the bike but you do need to re-jet evertime you put it in. (04 WR450)


Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now