I never use Manleys, All I use @ the shop is Ferrea. They have a 5.40" INDY SR/440-1/EZ specific valve in the 6000 series & that's what I used W/ a 33 degree back cut, & 5 angle VJ looking for low/mid lift #s. My heads are 236 @ .300", 326 @ .500"

I don't recall my exact exhaust #'s but I remember they were not great, peak was ok but low/mids were shoddy, although I don't port/flow much BB stuff, the #'s were weak compared to our SB heads. Peak was in the high 240's I think with no tube. I've made over 800 HP with a 1.60 exhaust valve flowing 250 cfm, so exhaust flow is a bit overated IMO.