what are some of the best supplements i can take to maximize my cardio breathing power?
Phosphates is your answer.
There are several phosphate products out there. Phosphates oxygenate the blood so that you carry more oxygen... endurance athletes have been utilizing phosphates for years as it is NOT considered blood doping and is perfectly legal.
NOTE: a little phosphate goes a long way. Do not exceed recommended does of phosphate products or you will find yourself on the can for quite some time.