#define NOS_MULTIPLIER 1.15

public OnPlayerKeyStateChange ( playerid, newkeys, oldkeys )
{
   static veh, Float: velX, Float: velY, Float: velZ;

   if ( (newkeys & KEY_FIRE) && IsPlayerInAnyVehicle(playerid) )
   {
    veh = GetPlayerVehicleID(playerid);
    GetVehicleVelocity( veh, velX, velY, velZ );
    SetVehicleVelocity( veh, velX * NOS_MULTIPLIER, velY * NOS_MULTIPLIER, velZ * NOS_MULTIPLIER );
   }

   return 1;
}