I prefer the billets over the UPP. With the clamp on filters attached to the carbs.. they liked to bounce. This was even worse with longer filters.. i didn't like that.. I liked the more solid mount with billet intakes and the sturdy mikuni boots. I've used UPP, BOSS, WK, Pro-Design and Chariots. Chariots are my choice.
.
I've never had a problem with fuel flow.