I use Keleman Motors in Geelong, they are mazda specialists, and very good. Still use them even though I'm northern suburbs these days. For south east I'm less sure but if you ask on the facebook groups you should get some helpful suggestions. One fellow Merv (?) comes strongly recommended, can't remember full name off top of my head I believe he's an MPS specialist.
The fault you are describing could be failed turbo seals, or blocked turbo oil return line... My first thoughts given you are being referred to a turbo specialist. It's a relatively common issue although I only saw it myself at 250000Km due to coked up oil return line rather than turbo seals.
I feel confident recommending Kelemans although they are a long way from you on the east side.
"Blue Meanie" 2007 Aurora Blue MPS 3 - 18x8.5+44 SSR GTX01 - 235/40R18 Michelin PS5 - 3.5" ETS TMIC - CPE stg 2 mount - HKS/CPE BPV - 2XS inlet - 2XS short shift - Corksport turbo manifold - HT 98 octane tune - Leather/Aluminium handbrake - Momo shifty knob - 7" touchscreen - JDM Mazda Retractable dashtop screen assembly - Bespoke Raspberry Pi Android based GPS/Carplay and instrumentation - 36AH reserve battery and C-TEK isolator - TEIN Street Advanced coilovers 1" drop - Superpro bushings - 220Kw/410Nm.
"Lipstick" 2013 Velocity Red MPS 3 - 18x7.5+48 Enkei RPF1 -225/40R18 Federal RS-RR - CPE TMIC - COBB inlet - CPE stg 2 mount - COBB Stage 1 98 octane tune - COBB shifty knob - 2XS short shift - 2XS turbo manifold.