I always recommend the Bengio Bumper as my rib vest of choice. I went through several rib vests over the past 3 years, as I battled separated and cracked ribs at almost every race. I tried several vests, several types of padding, modifying the vests to fit and pad better, different seats, different driving posture… Nothing really helped. I kid you not when I say I put the Bengio on in the middle of a weekend it literally made the pain disappear. I could barely breathe without wincing in the kart and once I put that vest on I had zero issues for the rest of the season and was able to put the factory seat back in. I don’t know what it is about that vest, but it solved all my problems and I’ve been pain free for over a season now. Which is saying a lot because my ribs are now weaker than they were before I hurt them, since I’ve built up so much scar tissue in them.
I have no vested interests in Bengio, I don’t even know where to buy one, but I know have bad it is to have a rib injury and wouldn’t wish it on my worst enemy, so any time this topic comes up I always pass on what I think is the best product. I got mine on ebay but had to ship it from overseas. I believe there is an American distributor but I don’t know the name.