Exactly as mentioned above keeping the stock cat will be the quietest setup, its pretty much pointless buying any muffler to fit after the stock cat so it is a huge waste of money buying an expensive one, best option for the budget is to fit an Arrow, Mivv, Remus or similar decat link pipe
Also have you tried running just the stock cat? remove the stock muffler & go for a ride just to try it out, gives you an idea how little the stock muffler reduces the sound, it is mainly the catalytic converter that does most of the noise suppression
The Arrow (71613MI) link pipe with a resonator sounds good with the stock muffler