part by part what happens to the car as you remove the entire exhaust system? does it raise torque and or horsepower? does it drop them? raise one lower the other? do nothing at all but make the engine noisy or more pollutant? What exactly does the exhaust do other than keep air clean? is a tighter exhaust better by creating more back pressure?
As stated before, the catalytic converter is designed to reduce emissions on the gasoline engine. These parts also create back pressure on the engine. With factory manifold (s) on the actual engine, to run straight pipes will improve performance by about 5% or less, depending on the age of the vehicle! Performance car builders of the 80's found that by adding hearers and a tuned exhaust with less flow restricting mufflers and increasing the inside diameter (ID) of the exhaust pipes, the need to run open exhaust (straight pipes) was no longer needed, and a lot cheaper for the street/strip cars! By removing too much of the exhaust system, you may damage your engine. I do guarantee that every cop in the city and the local judge will love you! You will get tickets for Excessive t Noise! The dB limit for a car that is liquid cooled is different that those that are air cooled like the VW Beetle before 1975 the Corvair for the mid 60's ache models! My advise is if the exhaust is in need of repair, have it done, then you'll not have legal problems. Mind you that even though this is a mechanical condition, Insurance companies do check hoe many tickets you get, and adjust the premium accordingly!
the engine will suck cold air into the engine and warp valves immediately. Plus it will be loud. I ran a race car(86 Honda Prelude)on a half mile circle track and found that you need to run the exhaust at least half the length of the car to keep or even increase horsepower without engine damage.
