The Pro Gas Animal has minor, but performance modifications that are very effective to making high HP at low cost. If you read the attached link of WKA spec #705 rules it explains the complete specs. The Pro Gas Animal specs were developed for an economical engine to build with good race HP and have more durability as compared to the Alky spec engine. This engine package will be added to the WKA road race series and the Daytona Dirt race in December this year. The Animal Pro Gas class has been a huge success in WKA National Gold Cup series in 2013.
Pro Gas is a fantastic engine and had produced unbelievably close competition! Any club looking to improve/increase their 4 stroke numbers should very seriously consider the Pro Gas engine as an option for sportsman, junior and senior classes!