[ProwlerGT]

For something labeled "BIBLE" such as this thread is, it serves to mind that the last thing that should be present herein is arguments and knocking heads. Frankly: End it and go in peace. If people want to believe there is a need for back pressure then let them. If people want to believe there isn't a need for back pressure then let them. The truth (who I'm friends with) will be revealed to the person who is wrong if they are serious & honest with themself enough to do the testing to find out.

Besides that I will offer up my own thoughts by way of deducive logic removing all ego and machoism or thought of who is right/wrong.
Ask yourself these questions:

What is the stock exhaust system comprised of?
What is it comprised of on MOST vehicles?

Answer:
1. Pipes to channel exhaust to the rear of the vehicle.
2. Why do the pipes lead to the back? Why o why? Likely because the rear of the vehicle is the best place to put the exhuast for reasons of noise for one.
3. There is a Catalytic Converter - What is its purpose? TO FILTER OUT PHYSICAL AIR POLLUTANTS.
4. There is a MUFFLER - What is its purpose? TO FILTER OUT NOISE POLLUTION.
5. Using common sense and thinking since the Cat's purpose is for filtering out pollution and the Muffler (as the name implies) muffles noise then what do both objects cause as exhaust air passes through them? Answer: Restriction. Restriction of air flow speed is a bi-product of the Cat and Muffler which were created for different purposes, none of which were engine power.
6. Most people buying a passenger vehicle whether its a sports car or not are not concerned with even 1/4 of the issues discussed in ALL of 3SI's forums, therefore to make most people happy the factories make the cars quieter and less pollution prone.

Engine power has nothing to do with why a cat and muffler were put on vehicles to begin with and the removal or upgrade of such parts only comes into play with a Performance Based Sports car mindset (IE: A gear-head) as most of us on here are. Deducing said facts with common sense will (should) show you that removing the cat and muffler will relieve exhaust air restriction allowing the engine to "exhale" faster thus allowing it to run better thus allowing it to gain more power (Yet GAINING more power is an illusion that we often speak of. The truth here is that we're just unlocking engine power that was already there, but held back due to stock setup).

Example: Think of your MOUTH. Put a heavy duty Brawny Paper Towel over your mouth and BLOW through it. What happens? Is it easier to blow air out of your mouth with or without the paper towel in the path of the air flow? Do our mouths need back pressure to blow air better? No of course not. Don't flame me for my example, but just listen. This is just fundamental basics on air flow (whatever the source of the air). The paper towel is just as much a restriction of us exhaling as is the cat and muffler to the engine.

The only reason cats and mufflers exist is for reasons of pollution of NOISE and PHYSICAL air type. If you took off the mufflers and cats for most or all passenger cars IN THE WHOLE WORLD you would have noise bombarding residential homes as the cars passed by as well as a much higher pollution rate causing air quality where we all live to become horrible not to mention global warming if you believe in that theory.

Conclusion: Arguments if need be should be over good points. This argument ya'll have been having is an argument about NOTHING and common sense shows that. This is no knock at anyone's intelligence, but simply a review of facts. I hope this will help people and I hope this will put this unnecessary argument to rest.

Side note: I personally hold the belief that installing exhaust pipes larger in width than the diameter of the throttle body air intake orifice is a waste of time and just for show. I believe this idea goes along with what I've said above.