2 transformers, 1 each lane is a good option. I recently changed to a 10 amp, 0 to 30 volt power supply and found it to be amazing. The clean power is awesome, and the adjustability of the voltage is so much fun. I paid less than 40 bucks on Amazon. Well worth it.

Great Video!
I think what this is showing is how marginal the set power supplies are, specifically the amperage is almost adequate. I have not done this exact test but I suspect more amperage from the power supply would resolve this.

https://m.youtube.com/watch?v=1HzYlr1mJqw&ra=m

I like these adjustable voltage power supplies, they are less than $20 on Amazon. These have 3 amps which is about 600% more than an Aurora power pack.

Being able to vary the voltage allows you to tune in the speed and response of your car to your track and skill of your drivers - it is a real eye opener the first time you adjust it.