Im also a MAZDA 3 owner, yea i`v gone upto 160+ in it. first i had a pair of 15" and when i went to 130 kmph the car was jurkin abit. now i got myself 16" wheels, its more better. its stable, even at around 150, but as u pass 150 its a bit hard to control, cuz the rear of the car bumps for even a small hole in the road. i touched 162 or 163, but didnt want anything to go wrong, cuz i was going out of control. my one is a 1600cc. not sure about the 1500cc. just got my kit down, will fit it soon.
u can check out my website.
www.cardomain.com/ride/2222267