What about exhaust?
Remember that turbo's are spun by exhaust gases. Increasing flow on an exhaust will increase the flow of a turbo by increased turbine speeds. This is why a better flowing exhaust is such a popular upgrade on turbocharged cars.
There are three components to an exhaust system - the downpipe (starting right after the turbo), the catalytic converter (cat for short), and the cat-back exhaust (the rest of the exhaust piping after the cat)
upgrading the cat to a high-flow aftermarket piece (HFC), or a test pipe (TP) that doesn't have one at all is the biggest upgrade. the OEM cat is the biggest restriction of the whole system because of emission restrictions on production cars. The Ralliart and Evo X use the same cat, so any HFC or TP for the Evo X will fit on the Ralliart
Ralliarts must use a different cat-back than the Evo X for fitment purposes. The downpipe must fit the turbo, so if you're on the stock RA turbo, you must have a Ralliart specific downpipe - an Evo X turbo would need an Evo X specific downpipe.
Upgrading the cat-back exhaust (better flow, biggest diameter) can also help to a small degree. Downpipe upgrades are more complicated to install and net very little gains for the Ralliart. Why is that?
Remember that all these systems are there to function WITH the turbocharger. The factory Ralliart turbocharger is VERY small and has limited flow capacity. Sure, upgrading the whole exhaust system will flow more air, but the stock RA turbo can only flow so much. the factory downpipe doesn't restrict much flow compared to the output that the RA turbo is capable of. The cat-back exhaust can show some gains in power, but again, only so much since there is a limited amount of air flowing from the stock RA turbo anyway
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