This is direct replacement for the Airfix part. Like their rounded exhaust (part 72 482 see my other review) this is also a direct replacement for the kit parts. This detail set has the exhaust ends drilled out to save you the trouble of doing so. That’s especially helpful given the oval shape of the exhaust ends. The parts are easy to get off the casting block and a perfect match for the mounting holes on the base kit. Thanks to Aires-Quickboost for giving improved options for both exhausts provided in the base kit.