I've just finished fitting another exhaust to my Z - so I've got the old one for sale. The rear muffler section is the TRUST brand. The front section I'm not sure of but remember something about HKS when I first purchased the car. Sounds great. Not too loud at all. No drone. Kind of like a crisp smooth note. It kind of sounds like a BA XR8 - at work I used to think someone was stealing the Z, only to look at the car park and realise it was only another workers XR8 being driven One downer is that the internals of the rear muffler have let go, so it will probably rattle within the muffler. It could probably be removed somehow - easy or not. Asking $100 pickup (had a receipt for $1200 for it when I purchased the car) located in Newcastle. If you are really keen and serious I can post it, but it will probably cost $50 to $100 to post given the size/weight.
