whats the deal with the different sizes of Magnaflow mufflers?

i don't really understand what the different lengths, widths, inlets and outlets etc. mean for performance or sound....can someone please explain. Looking into getting a single in dual out Magnaflow

 

bump

 

The smaller and shorter the muffler and pipe, the louder. Smaller muffler also means less air turbulence. More turbulence could slow down the gasses as they go out and affect any hp gains.

Most gains are seen mid to high rpm range by just adding a muffler.

Go Magnaflow

 

thanks man i understand now

 

For reference I have an 18" Magnaflow, and I wouldn't want it any louder than it is now.....you can definitely hear me coming.