i'm on the beaches and dealt with a few places.
I'd recommend Joviant Peformance. Its not overly cheap but thats cause the parts are good and Brett really knows what he's doing - its pretty much just him but he works 6 or 7 days a week.
He's done a few $100k plus GTR builds and the work is supreme. My Gtst is in there now getting the engine replaced and like i said not cheap but i trust him and his skill with all things turbo. especially RB engines.
They outsource for machining and dynoing is done at Bromspec BMW next door but its all done well and overseen by brett.
He's definately not in it for the money only for the cars. Check his R33 GTR - monster to say the least.
Tweak it in Mona Vale is really good for parts. trustworthy and all their parts are checked and warranteed.
Just done Basset st from them - Superior Automotive Services. These guys are great, they build open top race cars and the work is 2nd to none, but they dont know alot about skylines. They do have a Dynodynamics 2WD dyno though.
As for envy, outside appearances seam good and i'd probably buy a close to stock car from them but i'll stick to Joviant when i want it tuned.