I have found Ultrex very good to deal with - Ultrex.com.au - good gear, good prices and great to talk with. The ship fast and always take the time to talk to you. Have bought Strut Brace and Front lip from them.
Also, 999 Automotive - bris and sydney, web and ebay - really know their stuff and good pricing.
Also...perfectrun.com.au - specialist importers with australian offices
And...japanparts.com a bit bit pricey but great range.
Adam from TuSpeed has always been helpful, purchased my Grimmspeed 3Port BS off him and also just purchased a Grimmspeed AOS off a rexnet forum member who purchased it off him with positive feedback.
Wolf Racing Products, I purchased a front lip for my STI and my brother purchased a front lip for his 2000 GC8 wrx, both fit perfectly and look great, delivery was good to considering the floods in QLD are bad.
Tuners I have no good stuff at the moment in terms of experience. Got my car tuned at Autotech but im not happy with it. It will be going to MSR now for a retune and have my headers fitted. My brother is getting his 2000 wrx tuned with Scott from Insight Motorsports coz MSR doesnt tune Power Fc so will let people on here know how both places are. I did email a lot of tuners and not many seemed to reply back to me so it showed to me they didn't really care. Not going to mention their names though.
Tuners - Chiptorque (Nerang, Gold Coast) have been good to me with a Ezyflash unit. Expensive for tuning ie Dyno time, but very good results. My "stock" betty is pulling just shy of 165kw atw with an "off the shelf tune".
Dropped it off on Monday morning to have equal length headers fitted as well as, 3 port boost solenoid, in guard cai, silicone turbo inlet, Air and Oil Separator and re tune. Expected to have car back Thursday or Friday. Received an email Tuesday afternoon that car is ready and not only was all the work above done but also my turbo was ported. My expected power figure was around the 210kw atw. My actual power figure was a wopping 231.7kw atw (which I am stoked about) . Michael was a great help and informed me not to change my turbo over as it was adequate enough to get good reliable power out of. Car pulls like a freight train . Would recommend MSR to anyone ;-). Way better than my previous flash tune, which didnt even use my cams or tune the fuel in right. And also cheaper .
My brother also dropped his wrx off to Scott at Insight motorsports to have a Power FC fitted as well as a Q45 Air Flow meter and a retune. Car runs great and the tune seems to be very good so far. His injectors are a little too big for his turbo as he was sold a turbo by some dodgy guy off rexnet claiming it was a TD0518G but turns out its only a TD0516G and hence the 750cc injectors are overkill. But Scott worked with this and the tune, cold starts great, idle sounds like a rotary though ahahahha due to injector size but once warm the car idles like standard and pulls hard. I would recommend scott at Insight as well as he is a friendly and informative guy and did a great tune on my brothers wrx. My bros wrx pulls a safe 168kw atw with a TD0516G, which IMO is good considering ive seen TD0518Gs only pull round 175-180atw by some other tuners, though he was expecting (and so was Scott) around the 210kw atw if the turbo was a real TD0518G.