Okay, "gain" is a lie but it got your attention.

"Regain" is more correct.

Both the UrS4 and the UrS6 have a moisture trap that is intended to keep fuel vapours from reaching the Manifold Absolute Pressure (MAP) sender in the ECU. The moisture trap is on the boost/vacuum line from the inlet manifold to the brass nipple on the ECU (leads to the MAP inside). The UrS6 moisture trap is down by the ECU and, perhaps, because it is cooler there, there don't seem to be any issues with the UrS6 moisture traps.

However, the UrS4 moisture trap is on the firewall rack. The orignal OE clamps tend to weaken over time, perhaps due to engine bay heat cycles. End result is the hoses into or out of the moisture trap tend to pop off the moisture trap, just enough so the ECU does not get a full or any boost signal. As a result, the ECU does not control the wastegate frequency valve (WGFV) and, therefore, all you get is wastegate spring pressure boost (about 6 psi). On a stock 9.3:1 compression ratio AAN with no software or turbo upgrades, this makes your AAN perform like a 160 hp 7A 20v non-turbo engine, a loss of about 67 hp. For $3 for a couple of small gear clamps, you can gain this hp loss back. See photo for UrS4 moisture trap location:

Image courtesy of Jeff S.