Why is it necessary for my 90' 740 turbo wagon to have two mufflers? Not dual exhaust, mind you...but one muffler after the cat, then one right before the tailpipe. Could I lose the one after the cat and go with a single muffler?

 

it is to make things quiet. I have run with one muffler when mine was broken. It was loud and you really want the exhaust gasses to exit at the rear.

 

It won't hurt anything just be a little louder.

 

If it's okay to run with one, why would Volvo design the stock exhaust system with two? I get that it's quieter, but is that the only reason?

 

As far as I know yes.

 

the 1st one is also called a resonator