Gentlemen;
Dozens of "devices" aimed at improving performace were marketed during the 50s & 60s without any real success etc.
This type was helpfull climbing a grade with low octane fuel, but didn't have a long "life span".
Today; even without any lead, the fuel is such that they wouldn't be of any value. The one described by Zeke (4259) might be worthwhile if you drive in the mountains however.
Happy trails.
