So as most people with the 02-07's do with their intake silencer, this mod enables you to delete your intake silencer, hear your turbo and BPV better, not leave you with a gaping hole in your fender, and most importantly save $$. Aftermarket units cost upwards to $50 and you can make one out of your silencer for as much as a black tube of RTV costs.
Rotary Cutting Device or Saw.
1. Take a grinder, saw-zall, or some sort of cutting device to separate the two chambers of the silencer at the thinnest part.
2. Make sure that you smooth out and make sure that the surface on the elbow is level.
3. Cut out a square off of the bottom of the silencer to use that as your plug. Use a pair of snips to keep honing down that plug.
4. Once you have the size right, apply a liberal line of RTV around the bottom of your elbow.
5. Run your hand around the mating surface and make sure that it is air tight, the sealant is evenly applied, and clean up the bead.
Now even if you don't connect it to anything, you don't have a hole in your fender and it blocks water or if you have it hooked up to your stock system, it will really open up your turbo sound. Enjoy!