I have it installed on my 05. Def. noticed a huge difference between open and closed. TurnWRX is right on where you have to cut and weld it on. When you have the cutout open all the way you will notice some vibration in the inside of the car. It doent bother me to much. The butterfly is only held on by screws. Since you have all that vibration you have to check up on those screws all the time. I did the mistake of not checking on them and the butterfly came loose and was rattling inside of the pipe. I had to get mine welded back on there so it wouldnt happen again. Those are the only bad things I had with it so far. Like I said beforey you can really notice a difference between open and closed. When its open you can really hear the turbo start to spool up, and at WOT you can hear all the air rushing out. And then theres the rumble of the boxer engine. I got mine cheaper than any exhaust out there, 350 installed.