early Q exhast tips - seperate manifolds?

[forecast]

While I was loading stuff into the trunk at the local grocery store, I noticed the insides of the two exhaust tips on my '90Q looked the differnt.

The LH (drivers) side was dark and stooty, the other a powdery white color. I stuck my finger inside and sure enough the soot dark one left a black print on my finger. The RH side left a lighter color on my finger.

I'm wondering if the two heads/manifolds are kept seperated all the way out, even through the last box in the exhust line.

This came after an hour on I65 at 85-90mph. I pulled into the grocery store after a weekend away before going home. So the car was off the highway less than 2 minutes before I shut it off. If so, what does this mean? Is the driver's head O2 sensor not working? Bad injector over there?

dan

[Q45tech]

Except for the H pipe cross over the exhaust is essentially isolated until the rear muffler where some mixing occurs, still enough isolation to measure differences in side to side emissions from tail pipes.Differences in cats? You didn't mention mileage?

[forecast]

149,000 miles.

After a few miles of stop and go city driving the pipes had an identical apperance.