FTO AUSTRALIA

Which is the most restrictive part of the exhaust system? Will I see any gains from just a catback system upgrade (2.5" mild steel piping and sports muffler)? A better sounding note that's not loud is what I'm aiming for.

Also, any recommendations for exhaust shops in Adelaide?

Looking for the best bang for buck upgrade without being a tightarse about things.

Most restrictive is apparently the Y-pipe. Most people opt for RPW extractors (about $550), but otherwise yes, 2.5 piping and make sure it's mandrel bent.

Will I see any gains from also changing the cat converter, but leaving the stock headers?

You will still see gains with stock headers but not as marked. Stock exhaust is 2.25 inch.Optimum is 2.5 inch mandrel bent with high flow cat.