Ok, first off. This car is Rear wheel drive so the engine prob has true duals with maybe headers. Second, The G6 engine isn't even near fine tuned as the G37 or the 350Z. Changing exhaust will make it sound different or even better, but you won't get that high end snappy racing sound. Haven't heard it yet on a mid class car.
very true, but the way you're going to get close to that is either by doing something small or going all out. you'll get a shitton of rollover(aka feedback) if you increase the pipe diameter, remove the resonator, replace the stock cat with a higher flowing one, etc. as proven via all the videos of the guys with exhaust on here.
if you replace the oem resonator with a higher flowing one(ie cherry bomb), you will get a slightly more aggressive tone. if that isn't enough, then go for a turbo muffler to replace the stock one...like I said, do small things until you get the desired sound. If you already know exactly what you need/want, then you can do it all at once and save money on piping, labor, and shipping.
I've dealt with 2 different exhaust setups on my first tuner car and then 3 or 4 different setups on my second tuner. I spent a lot of money experimenting with exhaust on those cars, but I now know enough about exhaust to be able to say that you can get close. the g6 isn't a tuner car, but exhaust has the same principles whether you have a I4 or a V12
the G37 has a completely different engine than your G6. the rev's are different, different manufacturer, RWD instead of FWD....you could spend 1500-2000 dollars on getting full and true-dual exhaust and getting your computer to not throw a CEL and get it to sound damn close to that vid, but you won't ever get it exactly the same unless you swap your engine with a G37...which would probably be more costly than going out to buy a used G37 (unless you do the work yourself).