We supplied and fitted one of each side by side on Thursday, both sound excellent, the customer who uses his daily opted for the resonated and the customer who uses his only on the weekend went for the louder non resonated system...
You can fit just the mid and rear, the Y is optional...
Pricing of the cats is because they're made on a much smaller scale compared to Berks...
We have another soon to be fitted to a 370z, so I'll update again with photos and sound clips too...