Just to put this out for others, I initially installed the Alpine Upgrade to my 2013 R56. Wanted more bass, so I bought the Integral Audio X9331 T-Harness to add a sub.
I went with the Infinity Basslink.

The Alpine upgrade comes with a harness that intercepts the X9331 harness.
I installed the Integral harness upstream, it worked fine, except when playing bass heavy songs like Pink FLoyd (Roger Waters and those ultra low bass lines).
I was clipping the Alpine amp. (Not the Basslink) Knew it was the Alpine as I heard clipping in all front speakers, even tweeters.
After some thought, I installed the harness downstream of the Alpine amp.
No more clipping, seems that the Sub was improperly loading the amp's input.

Thought this might be of some use to someone.

 

doing the same now, thanks.