I would tend to avoid RAC unless you can guarantee getting a good inspection centre. I've seen a lot of iffy fast jobs done just for the money and little return. On a largely unrelated issue, I get a bit irritated with RAC anyway, as they tend to hold themselves up as "authorities" on all things related to motoring, when plainly they are not. Their views on road safety are sometimes ludicrous, such as supporting "saturating the roads with speed cameras". That is enough for them to lose all credibility for me.
It would seem logical to have a trustworthy Mazda dealership workshop do it, but whether or not that can be arranged pre-purchase is another matter. There are so few of them in Perth that they can't really afford to be too sloppy as it gets around fast, especially on forums like this. I find Melville Mazda good but have no experience of others. There is, however, one dealership that I would avoid, located SOR.
CP_e Standback & PNP; CP_e 3" SS Downpipe; Corksport FMIC with Top-mount K&N filter & OEM Ram CAI; Turbosmart BOV; Dashhawk; Prosport Boost Guage; JBR solid shift bushes; DBA 4000 Wiper-Slot front rotors; Hawk Ferro-Carbon HPS Street front brake pads (@ 69,000km); Sumitomo HTRZIII's in 225/45 x 18