By the time you buy engine management, spend money on travel and then mapping for a standard B18 I don't think its worth the amount that it will end up costing you.
B-series engines run very well when they are running the standard cams and compression with the OEM ECU, I had my old EK9 mapped by a very good tuner a few years back and the dyno showed gains in the mid range and a tiny bit up top but when compared against the same car before and after mapping there was zero difference in acceleration which is the whole point in mapping
If the engine was built with higher compression or displacement and after market cams etc then it will be worth mapping and its also necessary
If you get a car up and running and ready for a trackday like you plan... After doing a trackday you will see that there are a lot more important things to improve on with the car than trying to make more power. Then once you have a good feel for the car and have all of the suspension and braking dialed in, you will start chasing lap times and that's when it gets expensive!