Cat Con removal questions..

Ok i want to completely remove the Cat on my car and keep the factory exhaust minus the cat. We dont have inspections here so i dont have to worry about all that crap. I know once i remove the Cat i have to get the spark plug fowler things and drill one out to extend the O2 sensor that way i wont throw a CEL light. My question is.... Does anyone know the exact dimentions of the cat?? From where it connects to the pipes?? And also does anyone know the size pipe i would need to replace the gap from the cat such as a pipe thats 2.25 but on both ends its expanded to 2.5... Thats just an example i dont know the correct dimentions. How hard is it to remove the Cat?? I dont want to have to ghettofy my shit and have holes where the exhaust leaks to make the car sound like shit. What gains will i see if this is done?? Is it worth doing for the performance i will gain? Sorry if this is kind of chopped up but im tired as hell and im thinking about what i can do to improve the performance for very little money. Thanks

Stock diameter of the 7g's I believe is 2.25". Your everyday 2.25" exhaust piping OR a high flow cat with a 2.25" inlet and outlet + a good exhaust welder and you should be good to go.

Just get a 2.25" test pipe off eBay. Will already come flanged. Can just drop the cat and install the test pipe. o2 sensor should be connected to the downpipe and not the cat I believe.

OK. Thanks.