After Market Alterations to Honda Fit

Get him a couple of those little solar powered fans that fit on the window inside the car. That should make it “cooler” :stuck_out_tongue:
Seriously, unless it’s in his name, let him “suffer”. He’s 18 and already got you to buy him a new car, don’t pander to his wants anymore until the car is in his name

www.carbibles.com has a calculator that will tell you exactly how much of a difference the change in size will make.

I would not use a K&N CAI system. For reasons others have mentioned.

It sounds to me like you need to take the keys and let him bum rides from his friends for a few weeks until he realizes the value of what you’ve done for him and knocks off testing your limits. And I speak as one who raised a few kids myself.