RE: Twin Exhaust Pipe w/Dual Stingers for Savage
I tried one once. I wouldn't say it ran lean, but it wasn't very effecient as this type of muffler is not a tuned pipe (or at least not a very well designed one). But it did run hotter than it should.
I ran it a long time, and it didn't hurt the engine. It was a pain to prime as you need to plug both stingers and operate the roto-start (or pull-start), and the option of blowing through the pressure line has it's problems (body must be off, pressure line eventually rips a round fitting, taste of fuel residue, etc,).
Positives were it looked cool and the body stayed clean.
I eventually bought a THS pipe.....quite a difference, more top-end power and ran cooler.