I really dont know too much about cars but I heard that if I change the airfilter to a certain one it will increase the HP of my 2007 civic lx a lot. What airfilter would I use and does it do any damage? Thanks I appreciate any help

 

k/n filter, it will not hurt anything, will improve throttle response more than anything.

 

k&n...it'll be less restrictive than stock, but probably not so much that you can tell...
it won't hurt anything either.