Drift Tengoku — September 2004 · Page 273

Several years after the ECV let drivers control exhaust volume from the cabin, A'PEXi introduces another exhaust-noise idea: a silencer whose valve is controlled by exhaust pressure. Once installed, it needs no operation or adjustment, and can stay fitted at full throttle. The article says it lets a loud exhaust be used more quietly on the street [historical product claims].

A simple construction and low price are welcome! Quiet, effective exhausts are fashionable, and Drift Tengoku has introduced many manufacturers' products. But I wondered whether young drivers were satisfied with such low volume.

A loud drift car can seem cool, and flow matters when buying an exhaust. Even so, using a loud competition exhaust daily is difficult: enforcement is becoming stricter, and there is the issue of consideration for others. Yet repeatedly fitting and removing a universal, plug-like silencer… [author's historical opinion].

…is a bit of a nuisance. But don't give up on a loud exhaust yet! Look at A'PEXi's new silencer: unlike a universal silencer, it can remain installed at full throttle.

The cutaway makes its operation clear. A spring-loaded valve opens under exhaust pressure. It only opens when the accelerator is pressed firmly, so gentle driving stays very quiet; pressing hard enough to develop boost opens the valve and changes the sound dramatically.

At A'PEXi, I rode in an FD3S using it with a GT Spec exhaust, a type which without a silencer… [historical review].

Only 5 horsepower lost! Stationary exhaust noise below 92 dB. The graph shows nearly identical power curves with the Active Tail Silencer and with no silencer.

The body text says the loss is only 4 horsepower, while the headline says 5. The silencer supplied with the GT Spec exhaust loses 21 horsepower by comparison. In-house tests reportedly achieved below 92 dB with GT Spec and PS Revolution exhausts .

The author describes this as reassuring for inspection [historical test claims, not a current compliance determination].

…doesn't meet safety standards. The sensation is somewhat like a wastegate opening. Lifting the accelerator to change gear closes the valve and quiets the exhaust; pressing again brings the exhaust roar back after a brief delay. Driving gently without boost is impressively quiet! You can leave it fitted at full throttle, and attaching it to the exhaust itself… [review continuation truncated].