Welcome to the forum.
We haven't done a lot of ecu tuning here. There are some companies that offer it for us, but Nissan happily reset the ECU tuning if they get hold of the car and we lose it. Instead, it's cheaper and easier to buy tuning chips like DP Chip, Steinbauer etc. Several people have tried cheaper solutions like the "No Limits" devices, which may be dangerous to the vehicle because there's no monitoring of engine conditions (coolant/exhaust temps).