Why did Toyota choose Double Wall Exhaust Piping?

I found these pictures in the exhaust reroute thread...

 

thanks to @Jrobb for the pictures

 

I did the reroute myself, but I never saw the pipe they cut out... I'm curious now too

 

Either heat (dissipation) or sound (deadening)if i was guessing.

 

When I rode in my truck behind the driver's seat, I could feel the floor vibrate at certain rpm from the exhaust... and the exhaust isn't even under there. Thing is boomy... need triple pipe (or a muffler with different acoustics).

 

I am gonna say most likely heat. When I did the rerouted the double wall section is only on the driver side, it's after the cat. It is the crossover section that goes from the cat, under the transfercase, and to the y pipe section

Maybe so it doesn't crush as easy since it's under the t case?

 

For rust protection ......

 

I wouldn't think heat dissipation would work since you are effectively insulating the inner pipe ensuring the heat stays in the pipe..... which would probably be good for emissions and efficiency. It would lower temps around the exterior of the pipe though.

 

Yes that what i meant. Dissipation was the wrong word. (just trying to sound smart and mad myself look stupid)

 

O and BTW im from the same town as Tommy Lee Jones! Love your avatar!