Looking for a few technical opinions here (not political ones

)
Would it cause any problems if my catalytic (sp?) converter fell off and I put in a straight pipe? O2 sensor is before the the cat, so it should be uneffected right? How about back-pressure?
Now, I try to keep my car as original as possible (
other than the turbo set up I'm looking into

) But I'm just curious. I am not exactly looking for a hp advantage (it would be like, what, 1 1/2 hp), I am more looking at not spending the $1100

for a little while longer (and a little growl is always nice

).
Any comments? Warnings? Cudos? Admonishments?
Thanks!
-Matt-