There is no crate in front of the auction house in the trade district of the SW horrific vision. This is where the Magic-lined Manifold is supposed to be for the exhaust part of the Voidfire Deathcycle.
When clicking the cycle in dornogal, there is also no dialogue option for the exhaust, only the other parts. Did the exhaust get removed, or can other people see it?
I have 1 mask on and have been running solo.
I was able to loot it with 2 masks only a little bit ago and have successfully applied the three main completable parts from Stormwind to the cycle. Mask count shouldn’t have mattered as long as one is active, but it’s possible it was stealth-buffed for this launch.
tried with 1, 2 and 3 masks, no box there, and still no dialogue for the exhaust on the actual bike in dorn
I’m having the opposite problem. I was able to loot the crate (think I had 3 masks on), combined it with the pipe and had the dialog box to put it on the bike.
Did that, but the dialog box to put it on the bike is still there (the other options for parts I already installed went away after installing).
Edit: Worth noting that the box doesn’t show up again for me even though the dialog option didn’t go away. Also if I run a check macro it says that step of the quest is complete for me, so maybe just a dialog bug?
just tried with 4 masks this time, and the crate was finally there
I have the exact same issue you are reporting.
my dialogue went away after turning it in, but your check macro you posted in another read returned false for me 
I got the crate thing but when i put on the exhaust on the bike … it still shows the option to put on exhaust … i cant find the 2nd crate now