alternative exhaust options

i was thinking of ways to improve/customize the stock exhaust to make it better flowing, tell me what you think and if anyone has results from doing this before. on the stock exhaust i want to cut out the resonator and possibly make a test pipe with an 02 sensor emulator(secondary) all the same size piping, going into a stock muffler. i was also considering cutting the stock muffler open to possibly remove some of the restrictions and improve flow, while maintaining good sound and stock appearence. the other option was to use a s4 exhaust as those would presumably(sp?) be pretty good flowing and obviously stock appearing.

my second thought was to do a full turbo back exhaust(no cat) in 3in SS, with a nice long glasspack resonator, and obviously a flex joint and o2 sensor emulator. the exhaust would probibly be mated to a WS oval muffler, which is a really good flowing and cheap exhuast that turbo honda guys use often(the sleepers like mine) 3 inch in, 3 inch out which would split into some stock styled tips.

the second exhaust system would definently add a BIG performance boost, and kill lots of turbo lag, you might get some flames out the exhaust especially if you use a BOV or a semi-atmospheric DV, which can be cool at times. since there is no emissions where my car is registered either system i choose would be cat-less. either exhuast system would be MUCH cheaper than an aftermarket exhaust system(a quality one), he im cheap, so sue me.

let me know what you guys think, does anyone out there have a full 3in exhaust on their a4? who else here is cat-less?