AT butterflys come loose on the spindles, crap build quality, and makes them a s**t to balance as the butterflys wobble about under vacuum
When they come loose, its a better idea to fix them than to carry on trying to balance them TBH.
The later ones are a lot better than the early ones though, design change apparently although I dont know the details.
Its certainly fiddly to fit, although works ok.
servo takeoff points are non existant
all the ones Ive worked on have takeoff point that are sufficient to still operate the servo, although they do get slightly weak if you are right down at 1krpm when you are braking, but not exactly the end of the world TBH
and the results from they are not as good as other makes
Youve recently claimed about 220bhp on them on a standard engine with little more than just go faster cams on the burpspeed car havent you? Cant see the Jenveys making any significant difference at that level.
Go beyond that though and without a doubt it needs to be Jenveys.
They look pretty and that is the only good point about them.
They look pretty, they fit neatly with standard slam panel and radiator, they give great power gains compared to the standard inlet, there are plenty of good points about them not just that one, although I still personally prefer the Jenveys hence Ive just swapped porkie spec over from AT to Jenveys, but I dont see why you are making out like they just wont work at all when in reality plenty of us have had decent results from them.
They arent the best product on the market, but they do still give good gains.