i am a new WRX 2011 owner. Love the car! I have STD cat back exhaust and a Cobb AP stage 1 map. I just purchased a Perrin drop in filter and found out that Perrin has its own maps for $180! I cant spend the money on a perrin map right now. Is it ok to install the drop in filter without affecting my tune. Is there anyone who has a Perrin stage 1 map and would like to sell or share? Thanks.