I'm driving MT Waja CPS, but for reference:

i. engine RPM at 100km/h?
About 3k. 4k rpm already 140. 

ii. how good is the sound insulation? compare to honda city? anyone?
Never ride a Honda City before. But most people say Waja sound insulation is quite good. But remember that CPS uses a sportier exhaust setup, thus louder sound after 3.5 k rpm. For me, the sound is so sweet.. 

iii. does the car stable on high speed e.g 160kmh?
Stable enough for me (but I'm already using 16" rims with R3 suspension) until 180, but the wind sound is just 

iv. the gear change for auto is smooth? how smooth compare tu myvi?
Never drove AT before.

Yup, always press till bottom. But sometimes when dragging, it kinda hard as the clutch is quite high. 

I heard people say that R3 strut bar is re-badge of Zenden.

Its actually depend a lot on the traffic condition of road where you often travel, like daily route from home to office and back to home again. If it always jammed, better to take AT. Less fatigue, especially when driving after works.

As for me, my work place is kinda small town/village area and only 3km from where I lived, no jammed. So, MT is the best. 

Anyone here wax the leather seats?