Too late, discontinued as of today.....

Dealer press release:
ST400 Boost Gauges Discontinued as of 01 December 2006
For a number of years now, the sales of the Stack ST400B boost gauges have been dropping to a level where it is no longer viable to offer the engineering support to maintain it as a product line. We have therefore taken the decision to discontinue the production of this instrument, and to obsolete it from our 2006/7 price list.

As the sales of this product have been so low, we feel sure that this will cause little or no disruption to your business.