you have got fuel cuts,as the standarde ecu is programmed to do that over a certain boost level,about 1.35bars.
Now why are you reaching 1.4bars,as the standard boost should be 0.9?
The boost is higher if you have fitted a special exhaust or air filter,or the wastegate actuator can be rusted,I had to change mine for that,and the boost can easely reach 1.5bars.
My opinion is to get something to monitor the boost as a gauge or the blitz dual turbo timer.Then you will have to check if your wastegate actuator is ok,and if it's ok you can modify the boost level playing with the metal restrictor that is on one of the hoses near the wastegate actuator.The smaller the hole in the restrictor the higher is the boost,but be careful,a very little difference in diameter will make a big one in the boost pressure.
It's even better if you fit a boost controller to set the level of boost you want,but you don't have to do it to solve the problem,and check your wastegate actuator before doing anything else as even if you will not have anymore fuel cuts with for example a special ecu,that doesn't mean that your problem is solved as if the boost level goes even higher it can be dangerous for your engine!
You have also two different ways of electronic upgrades.
The one used by RC DEVELOPMENTS,fittin boost controllers,fuel controllers,injection controllers etc. but keeping the standard ecu,or you can just set up the boost with the different restrictors and a gauge or a boost controller,and then fit a complete new ecu that will allow you to turn up the boost and will change the mapping.
You can for example get a ralliart sports ecu from irs in japan at 550£ and it will allow you to turn the boost up and will give you about 350bhp if fitted with a complete exhaust system and air filter.
You can also get a motec m48 or another gr.n ecu that is completely remappable for your spec by a pro with a pc,and can include launch control and bang bang,but it will cost more than 1500£.
There are many topics about fuel cuts you should use the search engine!