you wont see it on a dyno , but you dont drive a dyno , and that's the key , how it drives on the street ( manners ) dynos start at where curved Dists usually end , so all a dyno needs is total all in before the pull , but on the street you drive 75% of the time from off Idle to 3000 , you could see a power increase if its over advancing ( racing condition ) where its stll advancing above 5000 ( and yes it happens ) , the bonus is it allows easier starting when hot ( compared to a locked dist ) and there is really no downside , and in a correctly curved vac adv and you can add 1-3 mpg , win win IMHO
