What can be done to increase horse power and torque that will NOT avoid the warranty? I have a 2015 Honda Civic SI. Thanks for the help.

 

Anything that can be removed before taking it to the dealer, basically.

 

Things like an air filter can make a tiny difference. There should be a ton of stuff on how to fit a Civic with mods. That said, you just bought a car and it's not fast enough for you. Why not buy something else. Get a used Camaro, Mustang or Corvette or something.