I have a 400 ex with the e-series pipe has anybody taken discs out to make it quiter, White brother said it makes a big differnce. I have to tone it down a bit even tho it is not that loud but it is just not worth the aggravation anymore. White brothers said to take 6 out. Thanks for the help.
2002 400ex
ac nerfs
white brothers fr. bumper
e-series pipe and K&N jet kit

 

Check the packing inside the exhaust. By putting fresh packing in it will make it quiet. Do you have the spark arrester endcap on the exhaust? I have the endcap and running 12 discs and it is not very bad. It is a lot quieter since I repacked it. They need to be repacked every 9 to 12 months.

 

I went from 12 discs down to 8 when I first got my 400ex (I bought it used with the E-series already on it). It made a HUGE difference in the noise level, it's livable now. I also have tons of low end that I didn't have before. I might have lost a little top end power, but I can't really tell...

good luck,
Lorrin