Has anybody had any experience with these lifters? Hughes claims they are much improved over the originals?

Vmax has an oil groove in them.Had no problems.My problem was I had dead springs.

According to Hughes web sight, by changing lash, you can shorten duration anywhere from 5 to 20 degrees up to 4000rpm at which time they give full cam duration and lift per a regular hydraulic lifter. I'm happy with my combination ( engine and drive train ) right now except for my 60 foot times. I'm trying to move a very heavy car - over 4K. Wondering if these lifters with my existing cam would help.

I ran the old RHoads in my 340 and it ran great. Cam was 298 adv and .508 lift. It was a 10.5:1 KB hyper piston motor and with the rhoads lifters it had 230psi of cranking compresion which I imagine bled off with RPM as it had no problem on 93 octane. Ran that combo for years with lots and lots of passes and street miles.