i've done it at the local autoshop with decent price, $205(labour+tax).
I asked machanics to cut both resonators and install 2.5" stainless steel straight pipes in that place... It sounds just like the car in this video.
YouTube - 2008 G37 Stock Exhaust W/Resonators Removed
I think exhuast note became very very rasp, but definetely louder than stock.
Overall, i'm satisfied the result over the price i spent. Bang for the buck.