Exhaust Performance Exhaust Upgrades 3

Question 1

What is the purpose of an 'O2 simulator' or 'O2 sensor spacer' in some exhaust builds?

Accepted Answer

To fool the ECU into thinking the catalytic converter is present and functioning after a decat

Answer

To move the sensor to a cooler location for longevity

Answer

To add a second O2 sensor for better fuel control

Answer

To increase the accuracy of the air-fuel ratio reading

Question 2

What is a 'straight-pipe' exhaust, and what are its legal implications?

Accepted Answer

An exhaust system with no muffler or catalytic converter; typically illegal for street use

Answer

An exhaust system with no bends; it is always street legal

Answer

A dual exhaust system aligned straight to the rear bumper; street legal everywhere

Answer

A performance exhaust that runs straight under the vehicle floor; federally approved

Question 3

How does an aftermarket exhaust typically affect a vehicle's horsepower and torque?

Accepted Answer

It generally moves the power band and may increase peak power while potentially reducing low-RPM torque

Answer

It always increases both horsepower and torque across all RPM ranges equally

Answer

It always reduces low-end torque while dramatically increasing peak horsepower above 8,000 RPM

Answer

It has no measurable effect on naturally aspirated engines

Question 4

What is a 'heat soak' issue in the context of turbocharged exhaust systems?

Accepted Answer

Residual heat from the turbo or exhaust soaking into the intake charge and reducing power after heat cycles

Answer

The catalytic converter overheating the oxygen sensors

Answer

The muffler getting too hot to touch after extended driving

Answer

Thermal damage to the exhaust gaskets during track use

Question 5

What is the advantage of a stainless steel exhaust system over a mild steel system?

Accepted Answer

Stainless steel resists corrosion and rust significantly better, lasting much longer

Answer

Stainless steel is cheaper to manufacture

Answer

Stainless steel produces lower exhaust temperatures

Answer

Stainless steel reduces exhaust noise more effectively

Question 6

When swapping to a larger diameter exhaust pipe, what can happen at lower RPMs?

Accepted Answer

Exhaust gas velocity decreases, potentially reducing low-RPM scavenging and torque

Answer

Exhaust gas velocity increases, improving scavenging at all RPMs

Answer

The catalytic converter heats up faster, improving emissions

Answer

Exhaust noise decreases because the sound pressure is distributed over a larger area