You can't possibly be going 2k at 80 mph, even with 3.08 gears.Acording to the little tire/wheel calculator I would be going from about 2k rpms at 80 to about 2600 @ 80. I know the performance benefit would be huge going to the 3.73's. Especially over the 3.08's I got now.
I average between 16 and 18 mpg now. On the road I get about 21 max.3.55's will be a decent jump for someone that has 3.08's. You'll definitely notice the difference, and it will still be very streetable. 3.73's would be an even bigger jump, and the modular motors still seem to do fine with gas mileage even at slightly higher RPMs.
As far as I know the o2 sensors are the originals as is the fuel filter. I plan on replacing them all soon. The maf is also going to be cleaned again soon. The stock one died about a year ago. When I replaced it the mileage did not improve.Just curious, but how many miles do have on the car? The reason I ask is I wonder if your oxygen sensors are original or older than 100k miles. Also, have you cleaned your MAF sensor lately and done plugs, wires, filters, and checked for vacuum leaks? I think you should be seeing a lot better mileage than that.
That I was told wont work , by the way I placed a bid on the 3.73's .I was also thinking of picking up this: