Ah yes, "A" link has to be cut.
Solder link "2" to large pad. "A" means absolute, the unit is looking for 0-5V signal. More suitable for MAF type of sensors.
Linking "2" enables the unit to read a 2.5 bar MAP. sensor. A pdf version of the user manual is available to be downloaded on the HFS4 forum here:
http://www.aquamist.co.uk/vbulletin/...ead.php?t=2168