At 70 I am cruising at around 1800 with 3.31's, honestly find myself using 5th at that speed. I really think 3.55's would be perfect for this car.I remember when my fox body mustangs had 2.81 or 2.83. Going to a 3.08 which were automatic rear end gearing was an upgrade. Obviously everyone went 3.55 due to the low 225hp. I always thought 3.31 was a good in between gear. That's what I have on my car now and with 450hp, more than enough gear. At 80mph I'm hovering around 2k rpm. IMO, I wouldn't go any higher and more so if you're throwing a blower on there.
Just a street car. lol Part of me thinks if I add headers and gears I might be happy enough to avoid the cash outlay for the blower!@SVT-DADDY
What's your outlet? If you drag race on slicks every weekend get the 4.09s; hell go to the good old 4.56s if you have an automatic.
If you're the daily driving type, 3.55 is the max I would personally have on a supercharged 5.0 S550. In your specific case, I would leave your stock gears alone and put the money into the blower fund.
That's exactly what I am worried about!I had 3.73s and once I put my whipple on it was too much so I went to the 3.31 and the power is much more useable now.