Just a quick update. The taxi from Changi to Clementi/Ngee Ann cost was around $ 33.50 both ways ( 12:40 am arrival and 6:50 am departure). Although taxi line at Changi was about 20-30 people long it did not take more than 10 minutes. Followed F/T advice and declined black taxi and took yellow- Comfort cab instead. Great driver! Going home used online app.for comfort /city cab to order taxi- took maybe 4-5 minutes to arrive. Thanks again!