art a first side 62 of ring 61 engages the first end 28 of the velocity stack 21 and a second side 63 of the ring engages the carburetor throttle body the first side 62 and the second side 63 of the ring are held in place by hose clamps not shown or other holding means known to those skilled in the art in operation the ring 61 can easily be disengaged with simple tools from the carburetor throttle body and first end 28 of the velocity stack 21 the lip 42 of velocity stack 21 can also easily be disengaged with simple tools from the rim 16 of the air intake boot so that the velocity stack 21 can be removed a different velocity stack for example velocity stack 23 or 25 can then be substituted with simple tools as described above for the removed velocity stack 21 the velocity stack to be substituted can be chosen to increase or decrease the velocity and volume of the air flow to the carburetor throttle body thereby tuning the engine 39 s power characteristics to better suit the terrain or the rider 39 s skill level fig6 is a cross section view of another embodiment of the present invention air intake boot 50 is shown removably connected to different velocity stacks it is removably connected to short velocity stack 51 mid length velocity stack 52 and long velocity stack 53 fig7 is a cross section view of the velocity stack.