Are there any comparison articles on vintage aftermarket exhausts for Yamaha enduros?

Or any personal opinions and experiences?

Back in the day I had an LT3 100 that I rode for a couple of years stock.  Then someone loaned me a Hooker pipe for it.  That really woke up the machine, especially in mid-range to the upper RPMs.  Hill climbs were a breeze compared to stock.  It was louder and probably weighed half the stock pipe.

I have a Torgue pipe and Bassani pipes for AT and CT series machines.  Just wondering what anyone else's thoughts, preferences and experiences are.

I have all of the pipes you listed as well as a few unknown brands. 9 total. All of them were a noticeable improvement and no it doesn't just sound like an improvement. You can feel the difference.

The Hooker on my CT2 is probably the one with the most noticeable improvement. It's to the point where the newly rebuilt clutch slips with the Hooker and it doesn't with the stock pipe. 

I have a Frankenstein pipe on my DT400B that looks like a JR pipe that has a Hooker outlet welded to the back portion of the chamber. It turned that bike into a monster compared to what it was on the stock exhaust.

Some of my pipes have removable inserts that can be cleaned. Some can be repacked with fiberglass. Some simply have a straight open stinger pipe. I have added clamp on silencers to the open stingers.

I am always searching for any expansion chambers to fit my enduros. The prices have ranged from $95 to $600. I'm still searching for one to fit my DT100B. The pipes that crossover are the hardest to find. The pipes for CTs are the easiest to find.