to be honest, nothing could be further from the truth
there ARE gains to be had from bolt ons, if properly selected, and even more gains to be had with proper engine management tuning
out of all the parts that can be changed on this car, the air filter is the least important. Aftermarket ones will provide better (subjective) sound, and cold air intakes will provide more consistent air inlet temperatures at speed (and recover quicker when the car is left idling)
Go on Adam..... I'm intrigued about the bolt ons that provide gains.