Congrats on your purchase and welcome to the forums
It isn't the sound generator as such. The motor is quite noisy from about 3.5 - 4.5k rpm. It is even more noticeable if you get a tune.
6th gear in the auto is quite tall and the FA20 is a relatively revvy NA 2lt. This is very normal. Keep it above 2k when you want acceleration. Or once it is broken in keep it above 4k for the real fun.