Gapless rings are actually two rings in one groove that overlap so that there is no gap.
I used to use them in Formula Vee and Formula Ford engines where every last horsepower was precious.
I must say that I could not tell the difference between them and a good iron ring which would "break in" quickly. (something you want in a race engine)
Leak down difference on a broken in engine between gapless and non gapless was in the order of 2%.
Bottom line - in a high horsepower street car you will not be able to tell the difference.
My opinions obviously!
