I have an 02 WR 426 I did all the free mods and I was going to replace the cork with a vortip. I had a Yosh TEC kit from my exhaust on my 01DRZ 400S. I had the smaller endcap as an extra so I removed the cork(1 bolt) and the three surrounding bolts holding the spark arrester on the stock WR exhaust.Pull the whole unit out, next I cut the spark arrester off closest to the back off the plate with the 3 bolts (use a good blade.)The spark arrester will pull off and the Stainless cylinder piece will also come off. The cylinder is the piece with the one screw in it. Now the TEC piece will fit perfect in the end of the silencer and it has a spark arrester built in to it. Throw out the cylinder piece and the stock spark arrester,You can keep the cork if you like, just keep the flat piece with the three bolts in it. Make a gasket from thick gasket paper (You might have to grind the inside off the three bolt flange slightly.) It doesn't have to be perfectly flat. Make sure the gasket you makehas the OD and ID as the three bolt flange and the three bolt holes punched in to the gasket. Put the TEC in first, the gasket, the three bolt flange, and the three bolts. Looks factory.You might have to rejet. Its a little louder, It does flow better though. Going riding tomorrow will see how it does.