You have to turn on the voice instruction
Go to XGPS setting-- Driving direction- Voice instruction

Just to share my discovery on this app
Downloaded the full map on PG island from XGPS-- Setting--Maps.. 9.8 MB
The turn by turn voice navigation works great.. It does use the downloaded map.. EDGE/GPS only use when it auto recalculate a new path(auto recalculate is perform where i did not follow the pre calculate path)