I recently acquired a babied 95' GT.  It has 80,000 miles.  Meticulously maintained and bone stock with the 2.73 rear gears.

I plan on doing a cam/head and intake change on it soon and am having a very hard time making the decision.  The car is a daily driver - very minimal if any track time and sees about 50/50 split highway and city driving.  I know fuel mileage should enter the equation when owning a car like this, but nowadays, it does.

I have a GT40-explorer upper and lower intake with 65mm throttle body.  I intend on installing an E303 cam with a set of ported E7 heads with GT 40 stainless valves and a new timing set and gears.  It runs a flowmaster catback, but will be getting upgraded to no cats and an X pipe very soon. It also runs 245/45/17 tires.

My concern is that in combination with the lower 1st gear of our transmissions, I still want 1st gear to be useable and not so short and I often cruise at 75-80 MPH.  With that being said, 3.55's were starting to look like the obvious choice, however.....most guys are saying 3.73's.....?

I'm really confused and would like to do this swap once and not regret the decision.  Any help is greatly appreciated.  

I have a 1994 GT that had some small mods but the owner before me installed a 4.10. It was getting around 12 mpg if driven easy. I would recommend the 3.73. The 1st gear will shift fairly quick but you will regret going with the 3.55.  

I've got a 3.90 Motive gear in my 98 gt with a 5 speed,  It works great doesnt rev to high and also works well with power adders,  All gears a are functional..  THis is the third gear I have put in that 8.8 at $160.00 its a cheap investment.. factory 3.27 to a 3.73 to a 3.90 and definately 3.90 is my favorite..