[Ryland]

Originally Posted by toc

What's the point of asking questions to determine if one is following a possible solution, if the response is go source books on the subject?
And who is to say the books are free of errors...

You are right, there is nothing saying that those books are free of errors, but many of them do have formulas that have been tried, tested and proven over the years and as far as I know no one has proven those formulas to be wrong and I would link to an exhaust sizing calculator that I used to use but the last time I went to look at it the web site was gone, it did however use the same formula for figuring out exhaust size for a small engine running at low RPMs as it did for a large engine running at high RPMs because no matter the speed or engine size you want to size your exhaust to work with the engine, instead of fighting it.

The exhaust has a similar line of thinking, if the exhaust can be more freely flowing, perhaps it requires less energy lost in pistons forcing air out of the cylinder, as the back pressure is reduced. But I was reading somewhere that Lean Burn engines rely on exhaust back pressure. I can't recall where.

Again, when you put a back pressure gauge on your exhaust (threads in to the O2 sensor bung) what is the pressure that you are seeing and how much do you hope to reduce it?

So I figured who better to ask then here! Many exhaust websites claim improved fuel economy is possible with aftermarket exhausts. I've got no problem with stock or aftermarket, was merely contemplating possible mods and hoping for feedback...

If you are running your car at high revs and seeing poor mileage it is most likely because your exhaust is not tuned for those high revs so at that point going with a larger exhaust will help slightly with mileage, will it help you get better mileage then if you were not pretending to be a pro-racer? no, will it help you get above EPA mileage? most likely not.

The resonator's purpose is noise reduction. How does removing that, reduce fuel economy? It'll remove a restriction on air intake - isn't that a good thing for fuel economy?

The intake resonator works kind of like a fly wheel, it helps store the pressure caused by pulses of incoming air between the pulses so that the flow of air coming in to the intake is steady and smooth, in other words it's quite, removing that resonator prevents the intake from storing the momentum and forces the engine to start from scratch pulling every fresh charge of air in to the combustion chamber.