Adjusting Tune to Suit

Hello, I have A 2005 Subaru Sti with link G4 Plus and the car has had a complete engine build running a Blouch 1.5xtr turbo, e85 straight and few other supporting mods. The Car still has the Factory airbox and running 20 psi of boost maxed with the current setup. As a beginner in the tuning world i'd like to fit a proper Air intake for colder air and better flow and would like to know how to go about adjusting the tune to suit?

I Have taken the Starters Tuning Package course and before i start applying any of the knowledge i learn practically i'd like to know from the more experienced tuners.

I don't have much experience but I would imagine all you need to do is adjust your fuel map. Try getting into a cell, see what the difference in AFR is, and apply that change to the whole map as a starting point.

So main thing is on how your ECU is calculating fuel. MAF (mass air flow) or MAP (Manifold Absolute Pressure)

If it uses the MAF sensor, then changing the intake can more dramatically affect your existing tune.

If you use MAP, then its impact will be far more minimal.

If you are using the factory intake pipe (that runs under the manifold), then this was actually quite restrictive at the sort of boost you are running, in fact they usually will collapse at that sort of boost as they are made of fairly thin plastic.

If you've change that already to a upgrade pipe, say silicone, then the factory airbox isn't that restrictive as it flow fairly well and does breathe through the guard which gives it a reasonably cool airflow. The factory MAF sensor housing does also have some restrictions in it if that's still in place too.

Cold air intakes should in theory be within the capacity of short and long term fuel trim to handle.

However the best advice i can give, is logging. Learn to read logs for at least RPM, manifold pressure, lambda\afr. This makes then adjusting your tune so much easier.