Hey tenrat,
I have the HKS Pane Filter, the V-Tune and the Hitech Quads, and I did a V-Tune before and after the Hitechs at Docklands. I actually purchsed the Hitechs through STi at Docklands and Vin fitted them and applied his magic. Hitechs were $1350 as fitted by Vin.
Prior to the tune, the 3.0R 5-speed auto (5AT) gave 116 Kw At The Wheels (ATW). After the 1st tune, before the Hitechs, Vin achieved 128 Kw ATW. Then with the Hitechs, 131 Kw ATW.
Now if you are looking for bang for buck (value for money), the V-Tune at $300.00 is probably the best you can get. My car was 3 years old prior to the V-tune and I regret not getting it done earlier. Also, I achieved a slight improvement in fuel economy!
I was dissappointed in the performance difference that the Hitechs had made, but there are lots of threads on this forum and others that I had read prior to getting the Quads that indicated marginal gains for the 3.0R, and that bears true with my experience. That said, I am very happy with the sound, which improved with age (deepened). A nice quiet burble at idle, but enough to hear the engine (so I don't try to start it while it is already running

), and a determined sound when pressed for spirited driving,
I think the best thing you can do, is get two 3.0R's one with Hitechs and one with Phats and listen to them at idle and at drive by. Then you can make your decision. I would like to hear Phats Quads on a 3.0R, so I will be 1st up to volunteer mine as the Hitech example. Is anyone good at sound recordings or videos so we can put up a link for others?
I am in the South East as well, but no trouble to travel for me.
Kind Regards
Mark.