do I have 2.73's?

[Soon2beBlown]

My gears seem extremely long and they really seem to be making my car seem a little sluggish. I think I either have 2.73's or 3.08's? At about 107MPH I was at 5k in 3rd gear...I'm thinkin their 2.73??

What kind of 1/4 mile improvement should I see with 3.55's or 3.73's? Current one is 12.7@107. Will low 12's be easily attainable? I'm leaning towards the 3.55's because I'm planning a turbo setup in the near future. Heres the current setup:
90 GT 5spd 98K miles, powerdyne s/c w/ 9lb pulley(no boost gauge) 30lb injectors, 75mm maf, 190lph pump, bassani longtube with 3" bassani x pipe, and flowmaster 40 series mufflers with stock catback piping running on 10" m't slicks without a tune

 

[CManT1914]

What are you turning at 70 in 5th? 1750 rpms is 2.73's, 2000 is 3.27's so forth...

 

[blkstangman88]

i got 3.73 and im running at 2300-2400 rpms at 70 in 5th gear..........if u got loud mufflers (like i do) and drive the freeway all the time theres a nice drone that can put u to sleep...lmao

 

[maverick0716]

With stock tire size (25.7") at 107 mph in 3rd gear at 5000 rpm you would have 2.73s.