Note: you can use any item you want for this.
this also works if you set the speed boosters to damage boosters.
materials:
x1 overlay
x1 checker
x1 wire repeater
x1 item granter
x2 speed modifier
step 1
overlay
button
visible on start.
step 2
checker
step 3
speeders
wire the first one to x2 speed
wire the second one from a wire repeater to x1 speed
wire repeater has a 10 second delay (feel free to change the speed).
step 4
items
just put an item granter down and set it to -1 (your item(i used energy bar))
here is the finished product
