yes the speed is a little softer on the bottom but i found it has more then enough, the grp was just a little to soft , i havent tried the grp .28 i dont like the idea of the fuel economy going away, i have allways run .21's in my truggies in the past, the grp tuned is really good in the buggy, just wouldnt recommend the .21 for the truggy, i have actually run the speed and the grp in the same truck with the same gearing at the same track with the same tires and conditions, the speed just was able to make more bottom to clear the jumps better, as far as the straight aways and going from turn to turn they are about the same, fuel economy is really similar as well, i run the grp with the associated 2035 pipe with long header and 7mm restrictor with p3 os plug its an animal in the buggy and was fast in the truggy just didnt quite have enough pop