The one solution to the problem is to do what I did. I quit the game almost three months ago. I sold about 120 full gemmed out cars and what cash I had. I got tired of all the glitches and hacking. There are better racing games out there.
The size of the bottle only affects how long it will last. A bigger bottle doesn't increase the pressure. On a perfect launch a 10 lb bottle should be all that is needed in the game on S and R class. A 15 lb on slower cars. Too big of a bottle is added weight which will hurt you.