Yes I know they open at idle, so yep making new intake to accommodate the return pipe.
I was only concerned they would melt as they will see heat they were never going to see mounted after the cooler. And if they did happen to fail I had visions of crap (Hard plastic) finding its way back to the intake and into my comp wheel..... I've had a look at the plastic, its looks pretty sturdy stuff tho.
I'm not expecting it to happen, I'm sure nissan built them to take 10 times the heat they were ever going to see. But it doesn't cost to ask, and maybe avoid a potential headache.
and as for cheap, not really - and thats when you can get them.