Im currently gathering as much info as i could, and it seems that 3M C70 will affect STag as well as GPS signal.
Somehow there's one forumer claims that if u hold the STag near the window, it will work just fine. But still GPS signal is weak and even worse no signal at all.

Im using Huper Optik with Ceramic 70 Front + Ceramic 50 Side & Rear. Pricewise around 1.5k. But my bad getting poorworkanship from a shop which I spoted dust in my front tint and the shop dont want to change for new tint.

IMO, the 'safe tint' nowadays is not that safe d. coz the thief are using Parang and Axe to break the glass. Thus, the so called 'safe tint' still koyak due to contact with sharp object.

U cant compare the product when u leave ur car under the sun for few hours. The comparison is when u drive ur car, try to put hour hand near the glass, can u feel the heat or not?

As the tinted will allows few % of heat to go through the glass, the 'few %' will plus with another 'few %' and will end up with a lot of % heat in the car. From my readings, only V-Kool Tint will reject the heat and your car remain cool under sunlight exposure (not really know the result since im using HO).

its really small. so the shop say not cover. coz its handmade not machine. and the buble is due to dust inside. its not visible but i still can notice it coz im abit particular with my car.