Any suggestions to improve gas mileage for the 3.4 in the impala

Have anyone out there who owns a 2005 Impala with the 3.4 have any suggestions to improve the gas mileage in these cars, such as a different air filter ,plugs ect, I bought one of those tornados that go in behind the mass flow air sensor but what i found about that is it seemed like the air flow was not there and seemed to hold the car back like she was not free rolling and also her idle was a little rougher,also he is burning way to much gas then before, I just took it out today after putting a 1000 or more km's on her and now she seems to run alot better without it and the car do not feel like it's holding back when she is coasting with my foot off the gas, I think thoses tornado's, $ 150. in canada, are a big waste of money and a big grab for the company who makes them,I have buddies who have them in there impalas and say they are getting 10 -15 more km's per gallon then before, their full of crap, it makes you think you are because it says so on the box,anyone got anymore improvements for gas mileage other then that piece of crap tornado,thanks.

High flow catalytic converter and a Flowmaster performance muffler should help noticably but it may take awhile to break even from the expense of installing them. I would also go with an aftermarket airfilter like a K@N and remove any restrictions from the airbox. Then fabricate some sort of cold air intake for the system. Make sure your brakes are in good working order and maybe install some light weight aftermarket tires and wheels but here again its gonna take awhile to recoup the cost. Running the higher octane fuel may improve a half mile per gallon or so but the trade off for the extra .20 a gallon is gonna be real hard to realize.

Think about this:
At 20 MsPG and gas at $2/gal then you are paying .10 per mile. If you improve by 3 to 23 MsPG then your cost per mile is .083, a savings of .017 per miles. Round it off at 2 cents a mile and it will take 50 miles to get a dollar back. Exhaust system work = $250, Inexpensive Light weight tires/wheels = $800, Airfilter =$50 equals $1100. 1100X50=55000 miles just to break even.

Probably the best thing you could do though would be to modify your driving style, I'm sure you could gain a MPG or two just from that.

Pretty hard to make any gains on mileage that are cost effective. Parts and labor these days...! On Highway only 320 miles RT I get 34 mpg in my 02' 3.4. I've done this trip 4 times w/same results. But combined over the last several months I am averaging 23 mpg, but more in town than highway. Strictly in town is so bad it scares me, about 13.5 Argh! But I've learned to live with it as I don't put very many miles on per week, 50 is my avg. Yea I put the new plugs, new wires, new air cleaner (standard). Going with high test gas will get you other problems more costly, carbon build up and possibly burnt valves. Watch your tire pressures and rt foot about the best you can do. good luck!

Higher octane fuel from a name brand supplier instead of from some fly-by-night rag tag oganization will NOT get you burnt valves and Will HAVE more/better additives to keep your fuel system cleaner. Now for the bad news, do the performance mods and run better fuel and your car will perform so much better that you will not be able to keep your foot out of it. Thus your gas mileage will suffer instead of improve. (you're screwed)