3.55:1 gears would be a REALLY good compromise between wanting acceleration and wanting streetability, especially with the T5
tranny.
The best change I made to my fox-body was ditching the stock 2.73 gears (and you think 3.00s are bad!) for 3.55s. I picked up about 1000rpm on the highway in overdrive, but the difference in acceleration was WELL worth the whopping 1mpg I gave up on the freeway.
Depending on tire size and your engine combination, you could even go up to 3.73:1 gears, but it's going to be something you're going to have to decide. Check your local parts store to see if they have the books by Sam Reid on building High Performance Ford Small-blocks and how to rebuild Ford small-blocks, he actually puts all the engine and gear math in the back of them. If you know what you want to do, and are honest with the numbers you plug into those formulas, you'll figure out what gears you'll be best off with.
I've got 4.56:1 gears in my old Chevrolet pickup... they're fantastic around town, I'm at 40mph (speed limit on most streets in town here) in 2 seconds flat without ever hitting 2000rpm (
tranny shifts straight to 3rd in that time), and they're even better in the 1/8 mile when I blow some unsuspecting kid in his riceburner, F-body, Mustang, or BMW away on the street. But they absolutely suck on the highway, 5500rpm at 70 miles per hour... right below the redline of 6000... I seriously get 4mpg on the highway with it because all four barrels on the carburetor are WIDE open. If I had overdrive things would be a little better, but not by much. I'm going to be swapping gears out in the poor old thing REAL soon.
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1976 Ford Mustang II Ghia: 302 with a 600cfm Edelbrock carb, Edelbrock Performer 289 intake, Dynomax Blackjack headers, 2.5" exhaust with Flowmaster Super 44s. RJS 11-gallon fuel cell, C4
tranny, chrome 16" pony wheels, fuzzy dice, brown vinyl half-top, and painted in the tackiest color ever (harvest gold, that's why I call it "The Goldenrod").
Also have a 2003 Dodge Ram (lightly modded daily driver/tow rig/office/dining room/home away from home/workshop... I call it "The Big Blue Dawg".)