Lightening the trans-axle in a 116 type Alfa does make a significant difference to how fast you can get the gearset to go from 4th or 5th back to 2nd in a racing scenario. I put a lot of time and effort in this process and ended up with gears that looked like swiss cheese (all machine work done by Vin Sharp). Lightening also preserves the 2nd gear synchro somewhat, but you still have to learn not to beat the synchro by heel-toeing from 4th/5th back to 2nd every time. The gears in the 116 trans-axle are unnecessarily hard, so it take a lot of time effort and money to lighten them properly. Most people would consider it a 3rd order improvement, to be considered only after already having implemented a LSD box with 50% lockup ratio, mixed gear set from a giulietta/twinspark etc.