@Scott My car needs a new catalytic converter. and I didn't want to go and spend unnecessary $$$ on parts for this car. And I was going to bu a high flow cat.
To extrapolate, these high-flow exhaust system components are fine for a race car that is seeing 5,000 RPM's + constantly and wants to take the checkered flag, but realistically, is that the world your Corolla lives in? If your car is driven like that, beaten on and put away wet, trying to win the checkered flag in a race, pushing the RPM's to the red line, then yes exhaust components for high RPM, high flow use can be of help.
However, if your Corolla lives in a world where 99.9% of other vehicles do, that is driven for daily transportation to work and back, to the grocery store, etc., then these high flow exhaust parts can actually do
harm in the form of reduced fuel economy, reduced throttle response and power. At the RPM's that street driven vehicles see every day, it rarely ever exceeds 5,000 RPM's, especially when toodling around town. A reduction in exhaust system back pressure that these high flow exhaust parts provide can correspondingly reduce low-mid range RPM torque, which reduces fuel economy and throttle response. That's not what anyone wants in a daily driven street car of course. If the vehicle is a race car that is constantly being pushed to the limit with 5,000 + rpm blasts, then yes the high flow exhaust parts will increase
high RPM power, at the expense of low-mid RPM torque, throttle response and fuel economy.
It's a trade-off. Low-mid RPM range torque, throttle response and fuel economy or high RPM power with a trade-off of reduced low-mid RPM range torque, throttle response and fuel economy.
Be careful what we do with the exhaust systems on our Corolla's. For a street driven application, the stock exhaust system parts provide the best throttle response, fuel economy and practicality.
There's no free lunch. Have to honestly ask yourself what you want in your car and go from there.
I hope this helps you out.