local speedMultiplier = 2;

hook.Add("SetupMove", "CustomNoclipSpeed", function(player, moveData, userCommand)
    if (player:SteamID() == "This Steam ID" and player:GetMoveType() == MOVETYPE_NOCLIP) then
        local velocity = moveData:GetVelocity();

        moveData:SetVelocity(velocity * speedMultiplier);
    end;
end);