Don't waste youur time and effort using the search, ask a question thats what forums are all about
Anyway Ry6rr changed his full system not long ago and when dyno'd the difference between an Akrapovic slip on and the factory headers+cat was only a couple of BHP down on a full Akrapovic system, showing that the factory headers and cat do very little to restrict air flow, its a lot less than the likes of other manufacturers that you can see a 10+bhp gain.
However you might also need to look at getting a power commander as removing the cat changes the way the ecu reads the O2 sensor output and so will weaken things off
I have a bodis slip on exhaust, was thinking just breaking the cat out? The sensor is before the cat so would it make any difference to the sensor? As the exhaust gases have already past the sensor before getting to the cat?
Even with the sensor before the cat, it'll change how the sensor meters the gases, they will flow quicker and so won't read properly. Bottom line is, if thats what you want to do then go for it, the bhp prob won't even be felt, though I guess it'll sound like it has more power, but I'd suggest getting it on a dyno if you decat it to just double check the mix is within safety zone