Rollers or Sliders and at what wieght

[Crazy88s]

Okay I need to replace the rollers (open to sliders) in my buddy 125 and my mothers buddy 125 we are booth light weight riders I am 120 pounds and she is 110 pounds we do a lot of mountain riding, she needs more top end her scooter is slow for a 125 compared to mine, Mine is like a rocket compared to her scooter anyway what is the best weight to go for, for top end speed, and are sliders really better then rollers