Having the cats is only to keep it legal and meet EPA regs. Sure, the mfg tunes them appropriately but I figure it's a compromise and without the cats, one can get better tuning, better performance, cooler engine, and smoother overall. (IMHO based on what others are saying).
Once I get past end of warranty I plan to do some "performance" mods which will include removing the cats. Now, not that I really NEED more power but hey, I gotta experiment with chit during winter downtime yanno ..