Intake Boot 
On the 2017 models, Toyota made the decision to straighten the intake boot that goes from the air filter into the throttle body. Perrin makes an aftermarket replacement that performs the same function, in addition to deleting the sound tube. 
 

 

Headers

There are two types, equal length headers (which came stock) generally gives more peak power, and unequal length more torque lower down. One other subjective advantage of the unequal length headers is more rumble in the exhaust note.

Many reviewers have commented on the somewhat uninspiring sound of the FA20, and given that this car was never about the numbers, it is arguable that this adds to the overall driving experience. Another minor advantage is a weight saving from the OEM. 


Tuning
With a fresh air filter and a HKS Hi-Power exhaust installed, the car was tuned. Breathing through the uncorked headers, it gained around 20whp that peaked at 185whp @ expected 6,900 rpm. Torque also went up around 10-12%. One of the advantages of the Ecutek tune was changing the throttle map. After 8-9 tries, a map with a good balance of aggressiveness and drivability was achieved. 

 

 

Crawford Power Block Spacers

Cobb power blocks were installed after the tune. Installed purely on the basis of this article from Moto IQ which demonstrated how the increased intake manifold volume translated into more area under the curve. While there may have been some power gained under the curve, I felt the original powerband was a little more fun, so ended up removing them.