Better flow and horses. If you get the intake and the converter along with a muffler it is a great feeling.

can't think of any, I mean it couldn't be worse than the stock.

Overall this is a great product, that you can hear. You can feel the air passing through more effiently and you get a great gain of horespower. For my sunfire I got about a gain a 7-12 horses. The sound it lets off is just like air going through a can, almost an empty tin can sound, can sound throaty with the right equip.