That Z in particular looks kinda ghetto IMO... fully cleared lights, blacked out rear panel, and the incredibly 80's HKS sticker doesn't help either. However, I think the Hyper exhaust CAN look good on a nicely done car. I like the fact that it's different; I've never seen another angled out dual exhaust, and it sounds pretty badass too.
Example:
I think the above car looks DAMN nice with that exhaust. But hey, that's just me. I don't think I'd ever buy the Hyper exhaust, but I certainly don't mind it. I can tell I'm not changing your mind though :)