well I bought obx headers, and a magnaflow cat-back, so needless to say i'm not trying to cut corners, but I had to get a test pipe if I wanted to put the exhaust on, because the oem cat has rusted over flanges and bolts to the point where you can't distinguish one from the other.
testpipe:
Pros: allowed me to install my exhaust, Cheap, really not too loud at all (gf & mom approved), definitely not raspy, doesn't smell too bad
cons: still a slight smell, one that i don't mind, just smells like burning rich. but yes it is bad for the environment, so if you have the option for the oem or hi flow cat do that (I will when I can) Also it threw a code for me. I forget the exact number, but it basically meant that you're cat was not performing efficiently, which is understandable since it isn't doing anything, but you will still have the check engine light on.