I have the Fidanza and love it - especially in the lower gears (where rpms increase is quickest). I have the Nitto 555R (drag radials) on the car and on clean warm pavement they'll grip pretty well
if the clutch is all the way out to begin with - pure throttle (in other words). Marc set my idle at 850ish so it has no rattle in spite of the Fidanza, tho too I have stock cams. I LOVE the Fidanza. I have the stock 3.45 gear, BTW.
Ami's (514 HP Z (with a 410 gear), also has the Fidanza. But, with Pete's reground cam overlap the trans rattles like a "box of rocks" at idle in neutral. But, with the B&B 3" exhaust, the rattle mitigated to the point it is barely noticeable from
inside the car at least.
On the street with the stock rear (3.45) gear, the least bit aggressive start in 1st gear and traction becomes "iffy" -
even with a heavy throttle only rev through the tach, the 555R Nittos will break. Ami's Z with (essentially) the same HP and tires, but with the 410s is a different story. It will break traction on warm, dry pavement regularly at will in 1st gear w/o involving the clutch. 2nd gear on the street w/ the 410s is just too much shifting, so the 1-3-5 shifts is normal for her car...and pretty much the same for my 3.45 gear as well, come to think of it.
Anywayz....I love the Fidanza with either the 3.45 or the 410 gears,
tho I agree too that a 373 or 390 might be "perfect" for me. In any case,
the Fidanza stays! AND, if running the mountain twisties is your thing too, and/or running beyond the 1/4 mile trap speed, the 3.45 (I find) is quite excellent. (I can run the "Tail of the Dragon" mostly in 2nd gear - keeping right on top of the torque curve.