Everyone, i just thought id let you know that i put a Wr426 pipe on my 00' Yz426. I was in need of a spark arrestor, and had to drop the decibal level way down. Well it slipped right on perfectly and is much much quieter. Went from 100+ db to about 85. And, its stamped in the muffler that it has a spark arrestor and meets all off-road sound requirements. If you were like me and needed a quiet, spark arrested muffler without giving the aftermarket companies your limbs, then this is a great conversion. As far as power goes, there is a little loss... but it sure tamed down the powerband a lot! I like this because i mostly do woods riding, and tame power is best... but for MX'ing ill just throw on the Yz pipe and have that surge back. Just thought i'd let everyone know!