The difference it made in power is about 18bhp. The trouble in determining the difference is that the engine was the '95bhp' 30128 series engines, and I never measured the power before. What I can say is that the boxer engines never had as much power as Alfa claimed. The production tolerances, poorly finished castings, a less than claimed compression ratio, all took their toll on the power. If you get 90 bhp from a 95bhp engine you were doing well, so I am basing the power hike I got (to 108bhp) on a middle of the range engine of the same specification. At best, I may have gained 22 or so bhp, and at worst I gained 13bhp. The difference between my car and a standard '95bhp' car leads me to believe I got more than 13bhp though.
I have yet to post the power graph (remember that I got the car rolling road tuned, in Luton, Beds), but when I compared the power graph of my 1.5 against that of a standard 1.7 16v engine, the power was the same up to about 5,800rpm, where the 16v took over and carried on up past 7000, where it puts out over 130bhp. This indicates to me that the mods I did boosted the torque curve of the engine rather than the power, and that the increased power was just as a result of a better torque curve at the top end. I did not increase the revs to get the power. Obviously the torque didn't drop away as fast as a standard engine. This means that my car, although it doesn't have the '105bhp' cams fitted to the Green Cloverleaf, is more powerful, and as a result of the torque, easier to drive.
Now, that was on a 1.5. If you consider that a 1.7 has a better torque curve anyway, then if you get the same boost of the curve that I did, your 3000 rpm performance should be better than most 16v engines.
Food for thought?