You know a really easy way would be to put the car on a lift, put it in 6th and see if there is a governer.
My 15s felt fine at 120
You were risking your life way more than you realized. At 100 my 1.4 LT was so unstable that it scared me. And for me to be scared is something, since i've done 170+ on a sport bike and just as fast in a Porsche 911 GT3. Both of those runs didn't faze me at all because of how solid those vehicles were.
But I felt how unstable the Sonic was and immediately backed off. Please be careful, at that speed an accident would be the end of you, multiple airbags or not.
This^
I don't think our car was meant for top speed (especially not the 1.8). I'm going to stick to handling mods and not test the limits of the power increases in top gears
I felt firmly planted, no wobble at all, easy lane change, at 125. Admittedly not on the stock rim and hankooks. But also without lowering. What stopped me was oncoming taillights, I really need a closed track... but one with big long straights, as I don't pretend to know how fast I can take a given curve in this car.