hks evc IV

Hi all,

I’ve got an hks evc IV that i bought used. It is the one with a rotary dial on the left and 4 rectangular buttons on the right. Does anyone know how to adjust the boost pressure? I’ve fiddled with it and can’t seem to get the boost to go up or down.

this is the model:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33742&item=7982613348&rd=1&ssPageName=WDVW