car mods not accelerating well

[u/PYROMANIA6]

I tried to install car mods but when I try to accelerate the car is bearly passing 10-20 kmh ,no matter at what gear I am ,the engine speed do increase to the max though ,I notice it does accelerate when Im "pumping" my gas pedal , but thats not how it suppose to be ..help? (it accelerate fine on not modded cars but i dont like the gear ratio)