Iridium plugs increase combustion Hence creating more heat. If you are feeling increase in power and engine is heating up then its normal and problem can be solved by servicing your radiator. Cuore/Mehran has small radiator and requires servicing after two years of use.
If you are feeling decrease in power and engine is not performing upto the mark and heating up then its a bad sign. In that case return to your original plugs.
My engine does not heat up coz i serviced the radiator last year. I drove on rushy areas with ac on and engine was fine.
But I made a mistake of getting ngk 5 heat range plug which is a hot plug. 6 heat range ngk or 20 in denso is recommended for most cars in pakistan. At the time of buying i did not know this and relied on the shop owner and he gave me hotter plug.
A hot plug has more insulator around the electrode therefore accumulates more heat. benefit is that it does not let carbon accumulate on it and remains clean. Drawback is in high performance sports engines there is lot of combustion so if the plug gets hotter than 800 degree celcius it can cause pre ignition of fuel which ruins the pistion head.
Cuore/Mehran does not have a high performance engine so i think it will work just fine.