Here is the full list of all 32 Speed Limit achievements.
Complete normal mode
Complete Stage 10 on normal mode
Destroy the final boss' paint job
Complete Stage 9 on normal mode
Kill 5 enemies on Stage 9
Complete Stage 8 on normal mode
Complete Stage 7 on normal mode
Complete Stage 6 on normal mode
Land into water and drown
Complete Stage 5 on normal mode
Complete Stage 4 on normal mode
Complete Stage 2 on normal mode
Complete Stage 3 on normal mode
Complete Stage 1 on normal mode
Don't kill the bazooka guy
He just doesn't care
Enjoy the elevator music for 10 minutes
Enter the most famous cheat code
Don't miss a shot on Stage 1
Kill 100 conga line guys without dying
Shoot your future self
Shoot your past self
Don't stop accelerating while on a bike
Fail to enter the choppa
Take no damage when driving choppa
Fire exactly one missile from choppa
Complete Stage 10 by only moving left
Survive 5 impacts with plane debris
Fall through both plane wing holes
Complete easy mode
Complete normal mode under 30:00
Complete 2 loops in infinite mode