Best one to get is the one from IPD usa.It will add a bit but nothing too crazy.You may want to chip the ecu as well

Answer by butchdalton on Jul 3, 2009

Lupo, Hard to say for your car. I have on mine a Magnaflow cat-back exhaust. Added is an AEM Cold Air Intake that I highly recommend to complement your performance exhaust. Since I have not had my car on a dyno, at best I can give you estimates from what I have read and seat of the pants observations. The reading material suggests 5-10 horsepower increase for the cat-back exhaust, then a 5-10 horsepower increase directly related to the cold air intake. I won't bore you as to why, I am guessing you know how these things work. Before I had these upgrades installed, I could floor the pedal to the carpet, but the car did not move with urgency and authority. It was more on the side of economy. The exhaust was very quiet and road noise was fairly intrusive. I am referring to a 05 stock Mazda3. I had both installed on the same day, because I could not stand the economy sound and feel to my ride. At idle, the car has a deep burble sound, a sound that any passer by or a stranger pull up next to you at a light, they know something is up. The Achilles to this set up, is off the line starts that lead to sprints, you will always be coming up from behind. The exhaust has this "A" type personality bellow and the cold air take have a whistle sound, letting the driver know he is communicating to everyone else he has something mechanically onerous within. When on the pipe, the car just keeps inhaling all the way up to redline in 5th gear with no noticeable flat spot. I can tell you from experience, I witnessed with my own eyes, a BMW 335i did all it could to shake me for nearly 200 miles and it was not possible. I passed him and stayed in front. Both upgrades tend to give the smaller displacement engines the ability to counter punch, whatever a faster car throws it's way. Again, the car will not become quicker off the line. I don't know if you watch boxing, but a counter puncher gets stronger because of his posture and footwork throughout the fight. The same can be said about a performance exhaust and a cold air intake. They will get stronger and respond brilliantly if on the winding roads of Bluefield Mountains of West Virginia. And you will be a happy, happy man. Did I digress!!! Your car will be an outstanding ride for it's class.

Answer by mark_hensley@sbcglobal.net on Jul 5, 2009