like the title says, I was wondering if anyone knew how to stiffen up coilovers?

I have a set of MDU coils and i have the dampening almost maxed out but the car still scrapes a lil when i hit a dip driving at high speeds. anyone know how to stiffen it up more?

 

You need to replace the actual springs with higher rates. Because the whole point of coilovers is to have matched dampers to springs, this voids most if not all warranties, and your dampers' life will be shorter depending on how stiff your newer springs are.

FYI you won't be able to buy any of the aftermarket springs for our cars. The rates are weak compared to most sets of coils.

 

Really? I wont be able to buy any? I know I read somewhere people were able to buy some and switch out.

 

Raise the car. It is not the purpose of shocks to hold weight of the car and stiffening them won't do anything. Springs hold car weight, getting stiffer springs may help, but it seems you are having ground clearance problems.