What size motor kits are out there for the 400ex other than the 440 kits? Anything smaller?

 

Curtis Sparks and CT both make 416 kits out west that are AMA legal. Out east TC and GT Thunder make great engines in the same size. If you are not in a CC restricted class get the new 465 Stroker from Curtis Sparks. They sad it runs with their 330! Soon as I move to Phoenix this fall I'm having it done.