What heat mats do you use? (wattage etc)

i have a Habistat Twin stat set at 30 degrees with 2 large Exo Terra rainforest heat mats but the temperature isn't going more than 25 degrees mostly sitting at 24 degrees.

i didn't have a problem before because the tank they used to be in had 2 large exo terra desert ones because it was the old Gecko tank and wasn't as high by 45cm.

thanks