Exhaust Tone / Sound Changes

Hey all,
Still getting familiar with my late fathers 1982 GTSi here. So many times I wish I had him to ask questions about the car, thus why I depend on this forum for some answers.

Took the car out yesterday, and it was probably the first 'cooler' day we've had the car out. Lower 70's in air temp.

And right off the bat, she was backfiring like mad. Not just during the off throttle/coast moments, but even on throttle. Took it REALLY slow as usual to get things warmed up.

(Some Background) At some point, dad took off, or the belt for the air pump broke off to hot up the cats. It doesn't do the 3K rpm hold at startup. So when I start it, I let the car run for a good 2-3 minutes before we even move.

Anyways. The car will let you know when its ready to go. Retards the engine and you cant open throttle until she says she's ready. However yesterday as we were warming up, the exhaust sounded like a Subaru Boxer engine! Had that 'rumble-rumble' sound. I was concerned enough that when we parked, I actually get under the car and check that we didnt have loose or cracked manifold or anything. Didnt see anything amiss.

But a while later after more careful driving, THEN the original exhaust sound come back and we were back in business. Car ran and sounded great.

But I'm just wondering, what could've caused that 'boxer' sound, and how did it come back??
Thanks for your thoughts/input!

 

I wondered the same. Like it was missing, but no warning lights on the dash for the cylinder warning lights (which do illuminate). Maybe it just wasnt happy with the colder temps?