I've got a friend who had a Ford 408W bracket motor with gapless second rings (which I know suck) that ran 10.0s. He sold the car, and that guy dingle-ball honed the cylinders to break the glaze, installed gapless TOP rings, made no other changes, and ran 9.9s.
I've got Stock and Super Stock guys saying they only work on poorly machined cylinders, which doesn't make a whole lot of sense to me.
I've got guys saying they're only good for low-compression motors or low-HP motors.
I've got guys saying they only work with a vacuum pump, and I'd buy that.

So what's the opinion here? Do they work or not?

Also, do the gapless TOP rings have moly on them, or are they plain ductile iron?

 

I run a gapless top ring. The ring is a 2 piece design so there's still a ring gap that need to be file fitted.

On the plus side, when your cylinder gets worn or deglazed, unless the rings are in poor condition, they'll still have roughly the same leakdown pressures as new because of the gapless design. The area where the gap is will widen up but still won't allow blowby or compression to get past from a wider opening.

Gapless rings are a lot more expensive than normal rings but are well worth it.

 

Total Seal has the procedure and grit of the hone to do them right.
There is nothing wrong with them if installed correctly.