leave (something) on the table
v. phr.— «Even a car straight from the factory will run differently with computer tuning—especially if it is a performance-oriented model like the Mitsubishi Lancer Evolution or the Subaru Impreza WRX STi, equipped with beefy hardware like a turbocharger. “They’re so aggressively prepared from the factory,” said David Vespremi, who wrote “Car Hacks & Mods for Dummies.” “And yes, they left a little bit on the table. And that little bit is often what you get from tuning.”» —“Need a Tuneup? Become a Hacker” by Seán Captain New York Times Oct. 25, 2006. (source: Double-Tongued Dictionary)