Okay guyz, i had my hks silent hiper exhaust for over 3 months.
The exhaust does not sound THAT loud as the one from the www.hks-japan.com.
It's just a bit louder than the stock exhaust for the IS300s while u're driving.. but the sound that it produce is good when you open your windows and hear it. It hardly have any droning sound. And i haven't dynoed it yet to see if it had any hp gains.
I will be dynoing it sometimes soon.. if it doesn't have much power gain, i am swapping to an hks dragger II or hks hiper.
Cheers,
NarZ