Few digits:
Native free spring height for the VX and Trooper - 402 mm
Native free spring height for the Frontera/Rodeo - 389.5 mm
OME912 is designed to get 1" of lift for Trooper - 420 mm
OME913 is no lift replacement for Frontera - 390 mm
So, strictly speaking OME 913 will not give you any lift compared to brand new VX, it will just raise it to OEM specification!!! That's why no changes to shocks are required.
I looked under mine VX and what I saw was totally compressed bottom turns.
2001 Isuzu VehiCROSS (build in progress): 4JX1/A340/part time, 2" body lift, front Aisin hubs, rear Aussie Locker, 4.56 gears, OEM rear sway bar disconnect, AirFlow snorkel, cabin air filter
1980 Jeep Cherokee (assembling): 1.5" body lift, TBI, HEI
1987 AMC Eagle: stock