Tuned exhaust are only "in tune" at a particular rev range where the resonant frequency of the exhaust manifold is in sync with the engine combustion cycles. Th

Tuned exhaust are only "in tune" at a particular rev range where the resonant frequency of the exhaust manifold is in sync with the engine combustion cycles. They're not widely used outside of racing applications, because a road vehicle has relatively wider rev range than a racing machine. And they're ridiculously loud. A vintage Cosworth DFV racing engine only "works" at 7000-9000 rpm (or 8000-10000 rpm for later models), a pre-turbo 2000s F1 car runs at 11000-15000 rpm to about 14000-20000 rpm (before rev limits were enforced). It's a really narrow band compared to a road car that can run from 1000-6000 rpm, ie. is useful on the entire rev range. All modern engines have well engineered exhaust manifolds, though, but they're not really "resonance charged" like a tuned racing exhaust.