Hahn Racecraft makes a circut which prevents positive MAP signals from going to your ECU. It's a fairly universal installation (2 wires) for MAP based cars, and they have wiring diagrams available. Call them or check out this link:

http://www.hahnracecraft.com/auto/engine/fuelmapper.htm

 

I might be wrong, but Tee off a check valve for about every 5 psi in between the map and your tb... correct? This trick was like 5 years ago.

 

Older than that dude. I remember seeing check valves on some of the first boosted Honda's I'd seen...nearer toward 98 or so, and I can bet it was being done way before that too.