By right we shouldn't add water into the coolant reservoir. The proper way to add coolant is to use distilled water (50%) + coolant (50%). It's best to as the SC to top it up for us since they should have the coolant mixture ready at all times.

The reason why we should not top it off with tap water is because the boiling point for water is at 100 degree Celcius. The distilled water & coolant mixture has a boiling point at 106 degree Celcius. Furthermore, the mixture will prevent your radiator from getting rusty in the long run. That is why, try not to top up your radiator with tap water 

Note: Believe me, the radiator temperature can easily reach 90 degree Celcius & could achieve 98C when the aircond is turned off.

After a long trip on hiway(Bangi <-> Ayer Hitam) i found that my car not stable enough for high speed travel. I've manage to clock 185kmph(odometer) ~175kmph(VSP). So far mod for stability only UR front tower bar and UR 16mm Anti Roll Bar. Why I say such thing is whenever I overtake a long trailer(Container aka Optimus Prime with flight tech) after my City nose aka grill reach open space which is after finish overtaking, my car will sway a lil' to the right. What else can I mod to ovecome such situation? In mind maybe wanna instal UR 2 point lower bar. Maybe after this change tyre to 195 instead of current 185 (want to go 205 but heard a lot of scrapping issue so wanna play safe). Spoiler only duck tail atm. Maybe adding front lips and front cannard can add front gripping ability?