On a standard car it'll make no difference at all. When you start putting larger downpipes and sports cats on the car along with remaps to suit, the stock TIP becomes the weak link in the car's ability to get air into and out of the engine as quickly as possible. The reason the standard TIP collapses inwards on a modded car is that the engine is trying to draw more air through the TIP than it is physically capable of flowing, hence the rubber hose starts to collapse under boost.
You will definitely see a power increase with a good Silicone TIP on a mapped car with
exhaust mods, no doubt about it.