Full N75 control is not something all "tuners" can manage
Map switching for differing boost levels or gear based boost, is also not possible by majority of tuners for 1.8t
It can be done... all with N75... but your choice of tuner will need to be able to do this. those who cannot properly control the n75 will often offer external means of boost control via ebc or mbc.... BUT this is because they cannot tune N75 properly not because it cant be done, because it can and I do it all of the time.
Also... 0.8bar, is that the tial springs or the actual boost you see on actuator only pressure. I mention this as not once have I ever seen a tial spring rate achieve their figures... Usually way way higher boosts are actual, which if you want a decent Range of Control, setting the low psi via changing their springs will be important.. I set and check tials off the car with compressor and pressure regulator so I see what pressure the valve actually opens up... and a tial 0.8bar spring will open at 22-25psi in reality to prepare you.
regards
bill