I have 2 Evo 1.00 and had the same problems ..but ... have two fixes for you. One: on the muffler where the two half's join I drilled a small 3/32 hole and used a very small sheet metal screw ..this stopped the rotation of the muffler...Two: If you take the blue ring off and make sure that the throttle barrel is closed ...count the number of turns in till closed ...then back the needle back out 1 1/4 turns....your midrange and transition should be greatly improved

Cheers