All i will say is i had a milltek, loved it but it wasnt loud enough.
I then added berks hfcs, purely for the sound. Without doubt it was the best thing i did to the car, i fell in love with the car again, it was like giving the milltek viagra. I really do miss that sound. You do get a rasp but i liked it.
I can list off a number of people who have gone for the same combo - glrnet, spursmaddave, bockerack and coldel. Cant recommend it highly enough. You will love it