I am running advanced headers on my 6 cyl. AU and am very happy with them!
My mate owns an exhaust company in adelaide, and has done alot of dyno runs with different brands, and he has found advanced to be the best he has tested (overall). He also sells other brands, but strongly recommends advanced.
Basically i am really happy with them, and picked them because my mate recommend them and he wasnt out to make money on the sale, and I have seen his dyno runs. Also they are very easy to fit!! (if he is charging much for labour, do it yourself, its just about 12 bolts! (I did mine, as I was helping my mate to do my system)
AU2 S-pack Owner: Silhouette Black, XR6 Wheels, Tickford Sunroof, C2R rear bar, Checker Plate Floor Mats, Chrome Door Sills, Blue Backlite Dash, Blue Painted Brake Callipers, Advanced Extractors, Magnaflow High Flow Cat, 2.5" Stainless Steel Mandrel Bent Custom Exhaust, Genie Muffler. Sony Explode 50w x 4 deck, Kenwood 140w speakers (front and rear), Boss 1200 watt Amplifier, 12" Orion Sub in custom box. More To Come!!