I put an aftermarket exhaust system that a friend gave me on my '02 YZ426F. It looked to be a decent system, but the brand name plate was missing from the silencer, so I'm not sure what kind it is, although I believe that it's an HMF system. I was going to re-pack the silencer earlier, but I couldn't get the core out of the silencer, so long story short, I decided it wasn't worth messing with. I'm planning on getting a replacement silencer (that's all I need), and I want to go with an FMF system. This is probably a dumb question, but do the FMF slip-on silencers that are listed as being compatible with the YZ426F mount up to the stock header? If possible I'd like to keep the aftermarket header/midpipe combo that I have but mount an FMF silencer to it, but I'm pretty sure the FMF slip-ons are meant to mount to the stock header of the bike they're listed as fitting.