This may be common knowledge to some, but check out this simple way to get more boost: http://www.heysefamily.com/BPCmodpage.html
This really smoothed out the power curve for my 9000. Low end power was previously very weak, now very consistent & top end is of course better as well. Basically, the needle never drops below half-white, and is usually in high white-mid yellow during normal driving. This mod seems to make for higher idle, though. I'll probably change it back when I upgrade the ECU.

If this is the same sort of thing as a bleed valve, then I know a lot of people who are very happy with the results.

Bleed valve sits on the rubber pipes just before the APC. You are able to hold the boost for longer. Have thought about doing this on mine as it is only about £40.