straight through mufflers?

I've been looking at mufflers from different manufacturers and alot of the mufflers they sell are straight through design. Is that best way for performance? I'm no mechanic, but would that be losing backpressure and just for sound?

 

whats the reason for a straight flow? is it pretty much a straight pipe with the mffler around it to look stock or legit?

 

there are perforations in the pipe. the pipe is surrounded by an acoustic material that cuts down on sound. This allows less backpressure but will be louder than stock

 

Its also depends on wat sound your looking for flowmaster has an agressive tone and the usually the straight through design are more of a mellow sound

 

Aero Turbine is another straight through

 

Looks like a giant gun silencer.

 

Aero turbine and also wicked flow mufflers are pretty good mufflers that I think give a good sound