I'm running these on a 485 PV motor and have no complaints. On the other hand, I have nothing to compare them to, as these have been the only pipes I've ran on this motor.
I did run them on a stock stroke/bore 350 with hardly any mods (some fucking Toomey intake filter thing, VF2 reeds, and proper jetting). Not exactly the best on low end, when I added the VF2 reeds, It seemed to wake it up quite a bit more on the low end.
I'd like to try some Shearer SB's on the 485 motor, but these work for now, so I quess I'll save the $550.00 for something else.