I just got mine installed about 2 weeks ago! I must admit the sound is real deep and mean... I love it! The only complaint I have is that its not exactly the most subtle looking exhaust but I have a rear lip that helps hide it. My other concern was highway droning but that is definitely not a problem. It is surprisingly quiet on the highway so its perfect for roadtrips.

I didn't really notice much gains when I first installed it but about a week later the car felt much better and seemed to "breathe" a lot better at higher RPM. 4th gear is still slugish but a lot better than w/ the stock exhaust. This is my only mod so far and I definitely think it makes the sound of our boxer engine roar.

Heres some pix...

 

Very Nice. Can even see you in the reflections. Can you provide me with a sound clip. As I am interested also.

 

wow looks super nice. what kind of rear lip is that and where did u get them? Im getting one this week, and im concernd about the look. thanks

 

does anybody have pics of a Hks hiper, with out the rear lip?

 

Thanks for the compliments. I got the rear lip from a local shop, its a replica C-West. It was either that or the oem but I wanted to hide the exhaust more and I saw the c-west kit at a local meet so I knew it was what I was looking for.

As far as a sound clip, the HKS website has clips of the Hi-Power for a few cars....

HKS Website

Scroll down and look in the left-hand side column... its listed under "Other Information".