The 3.54 has always been the best all around gear. Many gear ratios are discontinued but we have tried 2.73, 3.21,3.33, 3.45, 3.54,3.73, 3.91, 4.10 and 4.56. Back in the day when we could not get better 5th and 6th gear ratios we would use the 2.73 gears for the top speed cars. When the 3.33 was available, the track guys loved it as it put the motor right in the sweet spot for high speed corners in the upper gears. The 3.45's were popular with the drag guys as they could use a taller tire and still pull to redline in the 1/4 mile. For the street the 3.55's have always been the choice, better low speed acceleration without too much wheel spin. The 3.73 was real popular in the Gen 1's as they made less power. The 3.91 seems to be the hot ticket for the Gen 5's, really helps the low speed throttle response. The 4.10 and 4.56's just don't work, even with a really tall drag tire. The gear is so low it slows the car down, not giving the engine enough time to pull the gear. For some, those gears might be acceptable for the Gen 5 with the new transmission ratios.
When you change gears you might consider a better limited slip unit. Notice how your car wants to go sideways in low traction situations? A better LSD will differentiate better and the car will go straight. There are numerous options for LSD's depending on the use. Quaife, Tru-Trac, OS Giken and Wavetrac are a few popular units. The Gen 4-5 LSD unit is a low-cost upgrade for Gen 3 cars.
Hope this helps.
