I ran O'donnell 20% for the last two years and had great results. Now its 40 bucks a gallon at tower + shipping. Im going to byrons 25% and hope it works well for me. O'donnell is the best if you can buy it at your local shop. If not go Byrons or Sidewinder. Im not a pro just my 2cent. I think 30% is for the top 5% of drivers that need every advantage at big races.