Hey terry im guessing you live in the uk :) yeah we having a spout of good weather atm though with good extraction you should not need to upgrade your lights have you looked into light cooling tubes ? also when the weather is hot outside its best to move your cold air intakes to take from the coolest room in your house it maybe messy but it will keep the temps nice and cool and under control. It may require a booster fan and longer ducting but its worth it in the long run for these unpredictable spouts of weather :) p.s do not select this answer please I cannot win the contest. wait for a 2nd opinion and then select one of them reason is I have already won last months contest and would not be fair on other competitors :)