"Oval tailpipes" refers to the shape of the exhaust pipes at the back of a vehicle, which are elongated and have rounded ends, resembling an oval. Full definition
A distinctive diffusor insert with vertical struts and the large oval tailpipes of the RS exhaust system terminate the rear. (topspeed.com)
The extrovert look continues at the rear, with a spoiler atop the tailgate as well as a re-profiled bumper housing a substantial diffuser element and a pair of large oval tailpipes finished in black. (autocar.co.uk)
It sounds discreet enough, so it was a shock to discover, some miles later, just how loud and aggressive the note blaring from the twin oval tailpipes really is. (evo.co.uk)