Are you just calling it a mod because its a 600 in a 440 chassi or did you actually get the bored carbs, ported cylinders, twin pipes, high comp head, etc...? The reason I ask is because I dont see twin pipes...
It's a full race 600 skidoo race program, this is a 600 mod pistons, cylinders, head, 40 mill slides recurved timing and with single pipe it makes more bottom end then twin pipes better for riding in the mountain.