Picked up my 2016 370Z Sport with a MT in December. Absolutely loving it. I pretty much picked up the sport package primarily for the enhanced brakes. My previous car was a V6 Mustang and I had paid to do the Brembo brake upgrade aftermarket as the stock ones left a lot to be desired when doing "spirited" driving
Since I didn't want that feeling, nor did I want to add that as an aftermarket upgrade again, it made plenty of sense to just opt for the sport pack out of the gate. I am loving the cars engine performance, the braking performance, the look of the Rays wheels, and finally the lack of a back seat. This car does so many things right that I am unsure that I will really do much in the way of aftermarket performance upgrades. The clutch however... once all warranties are over I will probably go aftermarket on that. It has plenty of get up and go, the suspension feels tight, as I said the braking is very legit with the 14" front and 13.8" rear rotors, and it sits nice and low to the ground.
I have so far switched out the stock radio for a Kenwood DNX9990HD. It has some noise in the lines indicated something may need to be regrounded or whatever, but it is not engine wine and isn't too terrible so I'm in no rush to disassemble and investigate. I made sure to not get the tech package though as I took this Kenwood from my Mustang when I traded it and had planned on installing it in my new Z. Love the GPS and Sat radio and touchscreen and video playing capability etc.
Glad to be a part of the Z family!