Sure,
OK it's a cub. they are supposed to be slow.
Even though it's a slow cub you will find it's plenty fast for your first plane. I'm sure it will do over 50 MPH as is.
That plane probably has a high lift airfoil meaning that if you increase speed the lift will increase also and the plane will use it's speed to go up rather than to go fast strait.
It's better to think of ways to get more flight time, or more thrust for this type of plane than more speed.
Alot of people even go the other way and go for "how slow can I get this cub to fly?".
http://www.youtube.com/watch?v=VvSWSNDzFsw