Has it had a new diverter valve recently? They're a common failure. Especially after a remap, the extra boost pressure is often enough to split the diaphram. With a healthy valve you actually can't hear the boost anywhere near as much as with a split valve. If it's sounding 'hissy' on boost this would be one of the first things to tick off. Get an oem vw revision G.
PCV and cam follower are worth doing too, as they're also cheap and quick.
It's a good idea to get it scanned. If the 'jolt' is caused by a misfire it should throw a code. Coil packs fail and cause misfires.
It could be any number of things. The dv, pcv and cam follower should arguably be renewed every couple of years anyway, so sort those as well as a scan, then take it from there.
