There was no WEP for DB601 A1/Aa, only a special take-off boost. There is nothing that indicates that 1' Minute 1.4/1.45 was used for anything else than take-off or above 1-1.5 km altitude.
http://www.il2bugtracker.com/issues/40#note-10
http://www.il2bugtracker.com/issues/40#note-11