Hyper 8. Also, you may want to look into a good quality .21 if you want to be faster. Most of the higher end .21 will blow any .28 out of the watter! If you don't believe me, look in the magazines and see what engines the pros are running in Truggies. Almost all of them run a .21 and they can legally use a .28 in their races. If .28 were faster and they can use them in the Truggy class wouldn't the pros be running them?

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