The nitro fuel cooler does lower temperature by 7-10 degree.
Also you can notice the fuel tank has less smoky hot fumes in the fuel tank.
The engine can go leaner than normal setting but maybe about 10%-20% max. ( 1 - 1.5 mins + )
I don't know for sure it will give you more than 10+ run time but it all depends on your engine configuration, engine condition, tuning, clutch setup, tires, track condition, layout, weather, fuel and driving style.
If all these mention working in your favour, it will go over 10+ mins or else it will not