Thanks for the inputs, I was considering stack 27 and stack 22 of Blk 904 (both Changi road facing as I enjoy the view), stack 27 was a v high floor while stack 22 was a 5th floor below unit at similar cost, I opted for the higher floor one.
i actually went to the nearby HDB block and I thought that on 16 floor the road noise is minimal.
hope it makes a difference to negate the road noise too! Would probably engage ur service when the time comes to get keys