As per aszyd, the washers should go at the muffler inlets, not the y-pipe. That said, I do not recommend the washer mod as it will blow hot gasses at the rear wheel speed sensors wiring. I tried it for a short period, liked the sound, then had some tees fabricated with orifice plates to regulate the sound and curved exhaust tips to direct the hot gasses toward the ground. Redneck Engineering at it's finest.
It worked very well and was fairly cheap (IIRC, ~$150 for parts, welding, and cutting the exhaust pipes to make room for the tees), but, in hindsight, I think I would have been better off spending more and getting a louder exhaust.
WARNING: Putting holes in the exhaust system can allow exhaust gasses into the cabin. With a properly tuned/maintained modern engine and catalytic converter, that shouldn't be a problem (but it could be). If your engine is running rich and/or you have test tubes, it could be deadly.