Exhaust inserts

I live in california and I am trying to figure out the best way to comply with the 96db law. I have an FMF pipe on my 2000 WR400 that I really like but cannot be modified to meet the requirement. What is your opinion on which exhaust insert works best? GYTR, pro moto billet, baja designs, etc.? Does anyone have dyno info on inserts? Your opinion is appreciated. :)

I have an '01 426 and have been asking the same question for months know. I have not been able to find any dyno results for any insert. It seems in the context of quiet inserts and Q pipes, there is not a lot of data to determine which option provides the best performance but still meets the 96db sound limit. I was running a WB Promeg, but it will only pass 96 db at idle and the correct testing procedure requires about 4500 rpm, which it will not pass. I have a Promoto insert for my stock WR pipe for now and it seems to work well and still be around 96db.

I have a 2000 yz426. I modified a stock wr400 muffler to use at Silver Lake Sand Dunes. You need a S/A and a 96 db rule. I dont have dyno info but I can tell you its got a ton more power than the unmodified end cap had and is a bit quieter than my yz muffler. I took the end out, cut out the inner most tube and put the insert back in. I also never got db checked but you can here the difference easily! Somewhere between both bikes.

I at first used the Pro-moto Billet insert and liked, a lot more free flowing design than the stock or GYTR unit. I was sound checked at a local poker run at below 90db. I have since bought a FMF Powercore4 muffler which is louder but still supposed to meet the 96db rule, the performance difference between the insert and the muffler is quite a lot and dont plan to go back to the insert. just my opinion.

I have the Baja Designs and I really like it. It sounds good and I have been tested by the forest service in Oregon at 94db at 4500 RPM.

Jeff :)

I have a 02 WR426 with a PowerBomb header and a Core IV muffler. I just bought the Big Gun quiet core insert and installed it into my Core IV muffler. You have to square up the tip on the quiet core insert, but it will fit and it is much quieter. I have not had a chance to have it tested yet to see if it is under 96dbl yet.

If it works it is a $50 fix to quiet the bike down, if it does not work I will have to buy the Q pipe. Thought I would spend the $50 to see if it would work.

I will let you know if it passed when I get it checked.

Dave :)

I have PMB. Compared to everyone else I ride with I am a lot quieter than everyone else I ride with, including the XR650's with Stock mufflers. I wish I had a DB meter, because I am thinking of drilling out some of the outside holes on the insert. It appears they designed it that way to open it up alittle.

I tried the PMB and it limited the power. I now have the ProCircuit 496 (PC496) which meets the 96 dB requirement, but allows power comparable to the stock pipe without the cork. The PC496 is well worth the investment.

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