1) Go to HomeDepot and buy a matching Tap/Drill Bit. The drill bit should be big enough to accomodate a VERY long probe (3/8" drive extention will work).
2) Drill a hole in the bottom of the precat directly below the Catalytic Converter eliment, as close to the middle as possible.
3) Insert a long screw driver and begin to break up the Cat eliment ... this may require the use of a hammer and some time
4) DON'T breath that crap in ... once it is all out, thread the hole with the Tap and then plug it with a matching size bolt.
5) So that you don't have a bolt protruding into your canister, um I mean catalytic converter, note the thickness of the cat's metal shell and cut the bolt down to size.
6) Torqu down the bolt and have it welded later
7) Put back on car if you took it off and start up the car without the Y-Pipe on to "clear out" any left over debre (sp?) ... Rev the engine quite a bit for as long as the neighbors can stand it

8) bolt up the Y-Pipe and take her for a spin ... dont' forget to unplug the battery while doing this so that the ECU is reset.
9) Enjoy your new found power
