Hey... I was thinkin' today, and I have no idea what the concept of an upgraded exhaust does for the engine.

According to ads, and games, it adds horsepower, but I don't really get how.

Any one care to elaborate?

Thanks. :]

 

bigger diameter = more flow
manderal bends over crimp bends = more flow
more flow = more horse power (to an extent)

 

I mean, it makes sense, but why not, if that's true, just not include an exhaust at all and just have a big gaping hole? =\