I saw a 170 bus and remembered a map I once made for a first time traveler from Singapore to Malaysia, hoping that she would not get lost. That person ended up moving to Malaysia to work. Now I hear, most of Penang is lost in her.
There were couple of times in the early 2000s, I took this bus intending to just go across the border to Johor for some Malaysian food.
But once I was actually there, I ended up taking another overnight bus to Penang near the Thai border. After another meal in Penang, I would take the bus to some cities in Thailand.