low boost pressure, sometimes little boost, followed by loads of boost. inconsistant boost under the same conditions.
someimes sticking or worn actuators cause similar problems.
personally i dont recomend 710N if you getting remap etc the 710n worked fine on my stock a4 but after remap and extra work it couldnt cope plus the uprated ones look and sound great
is that a pic of n75J it or orginal......... im assuming the pipes exactly the same just you obviously have to extend the turbo pipe and alter postion of the wire that goes to it.
This S4 was mappd by AMD when new lol
It's done 91K now, and presumably it's on the original (possibly tired) 710's.
One of the first jobs I did when gettin my S4 was new 710's, N75, Tbb etc, and it ran soooo much better! Proper sings at full chat, and sounds like a jet on take off, love it!