HC - Let me tell you, its hard. It is possible to slide a 2 1/2" flex pipe over a 2 1/2" hard pipe, but its not easy. The leak was almost never right at a joint. I usually had to work the flex down the pipe a foot or 2 to make it to the spot that was leaking. Personally, I will probably never do it again. Its quicker to just replace the pipe instead of trying to shimmy a piece of flex over it. If you do try it, make sure you have plenty of WD-40 on hand. Lube it up well, and slide it on. Its gonna smoke like hell for the first day or so as the WD-40 burns off though.
i would think on a car that is up in the 37mpg range already would probably see the greatest gains out of this, kinda like holycow said basically, a 1mpg gain on a 20mpg car= 2/3mpg gain out of 40 mpg cars
the idea of performance modifications improving milage is sound if they are removing inherent inadequacies in the system. Take for instance my LW200 there are some inherent problems with this car. The Factory exhaust manifold is awfully restrictive and actually hurts milage by causing reversion in the ports. Once this is replaced with a more proper manifold milage improves. Contrary to popular opinion this car does not like a short ram intake but rather simply removing restrictions in the factory airbox has far more effect. Basically one must understand what is hurting milage and what can be done to help.
more air does not necessarily mean better mileage, your map sensor measures amount of air and compensates with more or less fuel in correlation with many other sensors
removing restriction from the vacuum of the intake or exhaust system allows a car to do what it does easier this is why a K and N filter would give you better mileage, because it allows air to more easily pass through it
My Echo accelerates at less than 1 inch of manifold vacuum in 5th gear at 30 MPH, about 1275 RPM. That's with a totally stock induction system, at less than 30% of throttle.
Last 2500 miles my average is 53.25 MPG, in a car that is rated at 32 combined on the new EPA ratings.
Probably haven't seen over 3000 RPM in over 1000 miles.
The Insight managed 22.5 miles this morning at 81.7 MPG going 45 MPH for 7 miles and 57 MPH for all but 1.5 miles of the rest of the trip, in heavy interstate traffic with a tractor trailer passing me 1 car length behind a Chevy HHR, who was barely two car lengths behind the car in front of him.
Total mileage today was 56.1 miles at 75.6 MPG. New EPA combined is 43 MPG.
K&N filers were tested in heavy construction equipment using oil analysis and they do not do a good job of getting the dirt out of the air, potentially severe engine damage.
I'll stick with the stock setup. I don't see any potential mileage improvement from any performance modification, since I never use anything close to the power I already have.
I get K&N because it's reusable. I've never noticed a performance or mileage gain from using them. If they made a resuable made from recycled materials I'd buy that but they don't.
I don't worry about the particles that get past these filters. You'd be amazed what can pass through an engine without damaging anything. I had a friend shatter a stock Chamion plug trying to pull it from his 3.9L Dakota(no idea why they torque the plugs at the factory so much) and he just started it and let the engine run until the ceramic insulator pieces and copper electrode passed out the exhaust and it runs great.
The majority of oil filters are rated to only 10-15 microns and K&N has a decent air filtering capacity down to 5. If particles that size don't kill it in the oil I don't see how it would in the air.