seems like you have the same results as me , and you can pull on the 600 trust me on this. check your belt deflection and remove a shim out of the secondary if needed . also make sure your carbs are openeing all the way, seems like the 5 dont from the factory. dan at the outdoorshop also chnaged my helix from a 51 to a 53/51 and that helped as well. and just so you know , wait till the sled breaks in and your running straight fuel in it ! if you think the mid is silly now.........