I knew they would be expensive but then again its a z =/. I haven't noticed any knocks but tonight I was taking a muscle car fan for a ride and I noticed something that was kinda like fuel cut in a lot of cars. There was no noise but the car kinda hesitated around 4500 rpm going WOT. Robert @ Z1 said he mailed the chip today so I am hoping to have it in the ecu the next couple days. I will feel a lot safer after its in.