I also own the purple fuses and the QSA red fuses for that matter. I think these tuning discs will give you more bang for the money. It is an instant result, not something you have to let burn in or listen carefully to tell if it is doing something.
4 for $200? At $50 a pop, sounds not only affordable but a great return on your investment with a 30 day money back guarantee. Just saying...
$50? A family of 5 every time they go to the big box grocery store spends almost as much on toilet paper... Go figure.