I have a Pro Systems gas and a Pro Systems alcohol carb. They are both great carbs. But I know SEVERAL guys using E85 on the street and braket racing them. I have ridden in a couple of them on the street. Mark Sullen's E85 carbs run flawlessly he has got the E85 fuel curve down. I'm not downing anyone else's products and I don't own any of Mark Sullen's products. But there's hundreds of people running around with his E85 carbs and singing his praises .