Stock Muffler with GYT Insert versus Aftermaket Muffler

4 replies to this topic
  • standup rider

Posted March 05, 2006 - 07:42 PM


I have a 99 WR400 with stock exhaust except for a GYT insert that I bought from the Yamaha dealer. This is suppose to be less restrictive then the stock exhaust. I wanted to see if I would get much of a power gain by removing the insert but did not notice much change including the sound level. Am I missing something since I have read that running without a insert makes things really loud. Are they maybe referring to removing the whole end that requires removing the 3 bolts?
I want to make my exhaust flow well so that I can get most out of my engine without getting real loud. Does the GYT insert do a reasonable job or do I need a aftermarket exhaust to make things come alive? If I really do need a aftermarket muffler/exhaust. What might you recommend that would get me a noticeable change over stock (with GYT insert) and still be on the quite side.
I would appreciate anyones thoughts and experiences on this matter. I have done all the free mods and will be installing my new JD jetting kit this week. I feel that this bike rips quite well as is but do not have anything to compare it to.

  • Numskull

Posted March 05, 2006 - 08:12 PM


you got enough power now. You trying to kill yourself? :thumbsup:

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  • pkcof

Posted March 05, 2006 - 11:36 PM


I just installed the GYT-R on my '05WR450F and the difference is definitely noticeable as long as all of the other free mods have been done also. The whole thing acts as a system from the airbox/carb(correct jetting)/exhaust and ignition mapping. People ride my bike now and cannot believe the difference between theirs and mine and have no hesitation in performing the same mods to increase the 'woohoo' factor !!!
I am not aware of the correct specs for your '99WR400 but i'm sure that you can find them somewhere throughout this forum in order to make it scream to your hearts content (and ride it like you stole it !!) ... good luck

  • Matty05

Posted March 06, 2006 - 05:00 AM


you got enough power now. You trying to kill yourself? :thumbsup:

Never enough power...............

  • Dan_Lorenze

Posted March 06, 2006 - 06:31 AM


The stock pipes on US WRs from 98-2004 are actually nice performing pipes when uncorked (with no insert in) but they're very loud. The GYT-R insert you have in there is a nice unit to pass any sound test there is, but they are restrictive to a certain degree. If you went to an FMF Q pipe or equivalent you would notice a substantial increase of power from bottom to top.. So yes, an aftermarket quiet pipe will out perform your stock/GYT-R combo.

I ran the stock pipe with a "Vortip" for quite a while... They're nice but too but restrictive..

good luck........


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