I am looking for a new exhaust for my R33 GTR, currently it has a powerflow 4.5 inch system, but its blowing and I want something that is quieter without compromising performance too much, the Powerflow systems are not my favourite anyway as they seem a bit cheap and are way too loud. I have seen HKS silent hi power systems advertised, I just want some opinions on a good system which is a bit quieter at low revs but gives decent performance when I rev it hard.