You guys talking about all this illegal stuff like he even cares. Obviously he wouldn't have done it, if it had bothered him. Yes, it's illegal, but he, like everyone else is just probably tying to get the most power out of his boxster. The nice thing about the cat bi-pass pipes is that they can be put back on for an inspection.
If the sound really is that bad and bothers you, I would just remove them and put the cats back on. Use the Maxspeed headers and after market exhaust and you can keep it all legal.