catback

cat +‎ back, sense 2 (the back of a cat, for riding upon) is modelled on horseback.

catback (uncountable)

1. The totality of components which exhaust gases flow through after exiting a vehicle's catalytic converter.
   • 2020 December 28, Donald F. Kuratko, Jeffrey S. Hornsby, New Venture Management: The Entrepreneur's Roadmap for Development, Management, and Growth, Routledge, →ISBN, page 340:

     Corsa Xtreme Catback Exhaust

   • 2011 July 5, Cam Benty, Chevy LS Engine Buildups: Covers LS1 through LS9 Models, Penguin, →ISBN:

     The downpipes bolt up to the APS off-road mid-pipes with copper RTV providing a seal on the flanges. Since there is no high-flow cat option, Howard says he plants to weld up a set of cats as he doesn't take kindly to the funky exhaust smell or lack of emissions compliance. Tanner also elected to stick with his B&B FUSION catback rather than the raunchier APS piece. The FUSION system retains the valving design used on the factory Z06 mufflers. This enables noise when you want and a civilized ride when you don't!

2. (usually with on, chiefly fantasy) The back of a cat (for riding upon).
   • 2010 April 21, Cory Herndon, Guildpact: Ravnica Cycle, Wizards of the Coast, →ISBN:

     Aun Yom's attack [on the lokopede] would require storming the carriage cars but only after sending in some leg breakers on catback. A well-aimed strike from their sweeper scythes should be able to take out a dozen legs at once.

   • 2018 September 11, Angus Watson, The Land You Never Leave, Orbit, →ISBN:

     Paloma reckoned they'd at least hold their own against the cats themselves and the Badlanders on foot, especially if those Badlanders were used to fighting on catback. So, as nets flailed and spears jabbed, she set about dismounting the riders.

• hogback