GTT orders are sent to the exchange when the last traded price crosses the set trigger price and after that, the order executes as a regular order. 

In the case of a market order, as the order was placed without a limit price, the order price that you get can be above/below/equal to the trigger price.

In the case of limit orders, the order will be placed on the exchange once the limit of the GTT order is triggered.

You will not get a price greater than the limit (for buy) or less than the limit (for sell).