They run better then a 353, but not hugely better in stick trim imo. A decent port job, really wakes up the 346xp, the 353 is pretty much what it is. Different cylinder design, and peak power is achieved at a higher rpm on the 346, so stock to stock it will cut faster in the same wood. It revs quicker too. Here I guess I'll put it this way, I wouldn't put a 353 top end back on a 353 if the cylinder was junk. I'd grab an oem 346xp top end in a heart beat.