"I believe" being the operative words there. You're entitled to your opinion just as everyone else is, but you haven't provided any "proof" either. Though it makes me chuckle that, in 2008, someone would believe that a car wouldn't run if there was not exhaust restriction, (that IS what you said - restriction is REQUIRED). Forty or so years ago, perhaps... but not today.
Some of y'all seem to be stuck mentally in archaic beliefs, many of which just don't apply to modern, computer-controlled engines.
I do this sh*t for a living guys... this is how I pay my bills. I'm MORE than qualified to present my beliefs as fact, yet I have clearly stated them all as merely my beliefs and my experiences. So why do so many people present their beliefs as factual info, when there is often a very big difference between the two? If everyone on CEG adopted the belief that grass was blue, would that make it FACT? Sorry guys, but no, it wouldn't.
Okay here you go.... these are not my beliefs these are facts striaght out of books!!
I am going to post a link to hotrod magazine explaining exhaust!
http://www.popularhotrodding.com/enginemasters/articles/hardcore/0505em_exh/index1.html
Mufflers -- Two Golden Rules To Avoid Power Loss
Inappropriate muffler selection and installation (which appears so for better than 90 percent of cases) will, in a very effective manner, negate most of the advantages of system length/diameter tuning. The question at this point is what does it take to get it right and how much power are we likely to loose if the system is optimal? The quick and dirty answers to these questions are "not much" and "zero." This next sentence is the key to the whole issue here, so pay attention. To achieve a zero-loss muffled high-performance race system we need to work with the two key exhaust system factors in total isolation from each other. These two factors are: the pressure wave tuning from length/diameter selection, and minimizing backpressure by selecting mufflers of suitable flow capacity for the application. If we do this then a quiet (street-legal noise levels) zero-loss system on a race car is totally achievable without a great deal of effort on anybody's part. Ultimately, it boils down to nothing more than knowledgeable component selection and installation, so let's look at what it takes in detail.
Muffler Flow Basics
We select exhaust systems based on flow capacity rather than size because engines are flow sensitive, not size sensitive. This being so, why should the same not apply to the selection of mufflers? The answer (and here I'd like muffler manufactures to please note) is that it should, as the engine's output is influenced minimally by size but dramatically by flow capability. Buying a muffler based on pipe diameter has no performance merit. The only reason you need to know the muffler pipe size is for fitment purposes. The engine cares little what size the muffler pipe diameters are but it certainly does care what the muffler flows and muffler flow is largely dictated by the design of the innards. What this means is that the informed hot rodder/engine builder should select mufflers based on flow, not pipe size.
A study of Fig. 6 will help to give a better understanding as to how the design of the muffler's core, not the pipe size, dictates flow.
Let's start by viewing a muffler installations, these are the in-going pipe, the muffler core and the exit pipe. Drawing number 2 shows a typical muffler which has, due to a design process apparently unaided by a flow bench, core flow significantly less than an equivalent length of pipe the size of the entry and exit pipe. Because the core flow is less than the entry and exit pipe then the engine "sees" the muffler as if it were a smaller and consequently more restrictive pipe as per drawing number 4. If the core has more flow than the equivalent pipe size, as in drawing number 5, it appears larger than the entry and exit pipe. Result: the muffler is seen by the engine as a near zero restriction. A section of straight pipe the length of a typical muffler, rated at the same test pressure as a carb (10.5 inches of mercury), flows about 115 cfm per square inch. Given this flow rating, we will see about 560 cfm from a 2.5-inch pipe. If we have a 2.5-inch muffler that flows 400 cfm, the engine reacts to this just the same as it would a piece of straight pipe flowing 400 cfm.
At 115 cfm per square inch, that's the equivalent to a pipe only 2.1 inches in diameter. This is an important concept to appreciate. Why? Because so many racers worry about having a large-diameter pipe in and out of the muffler. This concern is totally misplaced, as in almost all but a few cases, the muffler is the point of restriction, not the pipe!
If you still thinking putting a 4 inch dump after your headers and you still think your gonna make alot of power is sooo wrong. that makes no sense at all and you have yet to explain it. Please do!!!!!!!!!!!!!
