Hi, I am completely inexperienced with car modding/tuning and would like some advice. I want to install a new exhaust (cat back, not changing the cat convert) but I've heard that a new exhaust may introduce some problems. I was just wondering if a ecu tune/remap would be the way to go about things before a new exhaust. If so are there any recommended shops around Sydney that can do this?

Changing exhaust from BF onwards can introduce the engine light on the cluster as the O2 sensors get the s**t.
Someone like Autotech at Granville can help out with a solution to that and clear the codes. Not sure of other tune places. Give them a buzz.