Audi R8 exhaust guide for V8 and V10 owners: cat-back vs axle-back, valves, real dyno gains, heat shields, emissions law and what to check before you buy.

Planning a 911 exhaust upgrade? Compare valved systems, downpipes and tips, see realistic gains, drone and US legal limits, and pick the right setup.

How to install an exhaust valve controller: vacuum vs. electric valves, mounting, wiring, antenna placement, testing and the U.S. legal checks to run first.

How long does a valved exhaust take to install? Realistic hours for axle-back, cat-back and downpipe jobs, shop vs. DIY, and what adds time.