Hello- I will be picking up my new '14 BRZ Limited in a couple of weeks. Would like to disable sound generator with minimal effort- Could I just plug the hole under carpet in passenger's footwell using a 7/8" nylon plug?
Yes, you can just plug the hole under the carpet in the passenger's footwell. Not sure about the exact size, but you can use the plug in the glove compartment power outlet to test out the difference.
But why are you in such a hurry? You can do this at any time, but you might as well hear what the car sounds like as designed by Subaru/Toyota, and then plug it later and see what you prefer. You will probably not be revving above 4,000 very often for the first thousand miles, anyway.
I'm at 800 miles, and have experimented with the hole covered and uncovered. It's currently uncovered again, but I won't make a final decision on it until some trial and error after the break-in period.
-Z