As for report back... I didn't hav time to go castle hill to check out the place.. But I found another shop near chatswood which is closer to me. It at brookvale, it is a shop professional in installing exhaust, engine, brakes..etc the shop name is A&B nd on behalf of Ksport. they also do dyno testing. They r asking $100 for mid pipe install. Also for O2 sensor, for them to install it does not need to be cut nd hav the O2 sensor tools