Marco,
I can say that the car we did this week didn't have those issues with noisy the Milltek seems a very good system.
Below is a stock 370Z car against a car with your spec , stock cats/Milltek non resonated system and drop in panel filters.
I will be willing to fit some HFC's and let you drive the car for a short time to make sure they are to your liking thou.
any questions ask away.