Does anyone know if the wiring for the sub on the Interscope sound system in the 500 is there whether or not the sub is intalled?

I have looked at EPC but it's not clear with the descriptions?

The sub on it's own is only about £110, so if I could effectivley "plug & play" i'd go for it.

I know with the grande punto it is not pre wired in so would involve cutting into wiring up near the dash. Suppose sub wire costs money so would add up if pre-wired. However I don't know for certain if it is.