if your planning on upgradin g the whole exhaust system too,go ahead and do the air filter.if not....id say its just a waste of money.even a 10HP gain cant be felt(inwhich i doubt an air filter alone can give).its just a waste of money.if your after the sound difference..go ahead and change it.(tho i have no clue why anyone would spent their money to change an engine sound without any noticable HP gain is beyond me)id rather spend my money on making my ride feel faster than sounding faster.but...its you car so its your call.