my 91 did not have a third cat but was a resonator instead, car was stupid loud.

 

3 resonators, 2 cats, and 2 mufflers......seems like a buttload of restriction on airflow to me. I wonder if a good dual exhaust setup with just 2 mufflers, no resonators, and no cats would help MPG at all. We don't have emissions inspections here. I'm sitting at around 12-13 mpg city if I'm easy on it, after running some seafoam through the vacuum lines. Of course, at 120,000 miles, my cats might be plugged up(I don't know if that would set a code....I scanned my car while at my uncle's this weekend, and no codes at all).

 

Well! I guess I'm keeping my 3rd resonator haha.

 

well my old ls actually had straight custom X pipe coming off the two cats in front, making it real loud.

 

I plan on going the x-pipe route soon. Any sound clips?

 

look in the exhaust thread. link in the faqs.

 

so removing all 3 resonators will not have a great effect on exhaust tone or loudness?

 

then your car has some SERIOUS issues - after installing new ECU capacitors, I am at 20.6 mpg around town

 

I just deleted the two rear mufflers and left the 3 resonators, sounds great and still not that much louder than stock.