This is achieved by providing reduced intake valve lift and duration at low engine speeds for good torque, with increased intake valve lift and duration at higher rpm for optimum power. (topspeed.com)
The customer benefits from very good torque delivery and dynamic response across the entire engine speed range. (greencarcongress.com)
They are sold to look sporty (because they are different and cool), provide better torque without damage, and for additional security. (mechanics.stackexchange.com)