There were literally dozens of companies making inexpensive "look alike" pipes in the 1970's.  I bought one for something like $15 new at the Yamaha dealer that looked like the "Torque" brand but was a knock off.  

I was just a kid, the owner of the dealership showed me both and said the cheap one worked just as good as the Torque for a lot less.  I didn't realize at the time that the dealership owner, Mike Patrick, was a racing legend and helped develop the DT1.  He was just an all-around good guy who on that day saved a kid from blowing all his savings and birthday money on a more expensive pipe.

If I remember correctly, the "knock off" pipe was virtually identical, biggest difference was the heat shield shape was slightly different.  

Somebody posted a picture of a JC Whitney catalogue in one of the Facebook Yamaha groups. This pipe is a dead ringer for the one in the illustration. I’m starting to think that it is a JC Whitney pipe. I wonder who made them ?

I haven't posted in a few years, as I left to help start another site ... but I see you can use some help on this one > > >    It's a "Bob Bailey" pipe.

Happy trails, Dave / Enduronut