Any tips or tricks for modifying a blue go devil so that it will suck back through tight radius 90 degree elbows (such as those used between sections D and E on the 47 Putz.). ??? 

On our 47 schwings and my 61 schwing with the 4.5" boom pipe we modify the go devils by putting them in a lathe or drill press and shaving material from the center shaft of the go devil. This allows it to bend better to make it thru the smaller diameter bends but I don't think they are near as tight of a bend as on your 47 putz. 

that's a good idea, perhaps if we do that in addition to making the go-devil shorter by removing one of the ribbed segments , it may be able to pass through the tight 90's. We always suck a damp sponge first and follow with a go-devil for cleanup so I am thinking that chopping it down to only two ribbed segments will not be all that detrimental to it's cleaning ability.

16cell

What do you think about putting a few gallons of water in tip 90 then putting sponge and elevating boom so all sections have at least some fall...then suck back slow and gravity brings the concrete and water and sponge wipes the pipes clean.  Works pretty slick even on the putz 47 and as a bonus what's in your cylinders is real runny buying you some extra time to go clean out hopper.  Of course all that is contingent on actually having room to stand it up a bit to suck back!

we cut one rib off and they work fine and still clean the boom

I often suck a ball just a bit in the tip.. than a bucket of water and then another ball.. Does the job very good.