[insp3ctor]

Code:

if(strcmp(cmdtext, "/boost", true) == 0)
    {
    if(VehicleBoost[playerid] == 1)
    {
        SendClientMessage(playerid, -1, "[!] Boost deactivated. ");
        VehicleBoost[playerid] = 0;
    }
    else
    {
        SendClientMessage(playerid, -1, "[!] Boost activated! ");
        VehicleBoost[playerid] = 1;
    }
    return 1;
    }

tested