I can not really help in your area. The 3.0 si is already a 3.0 on steroids. I had a ecu tune added to mine and was only able to get another 18 hp amd 25 fp of torque out of it. I dinoed before and after.
SoCal Z Enthusiast contact me to get on the list. Events for like minded people and when you talk about your Z, we will know what you are saying.