Does anyone make a Knock Monitor that can be on dashboard, to monitor engines for knock levels on Mercury 700sci/similar engines with PCM555 computers?

We have 2007 700 SCI's and can only get 89 octane gas, so we add Boostane additive calculated to give ~93 octane.
We put a very mild tune into the PCM 555 computers from a reputable shop and have had no problems, plugs fine, piston tops good, but would like a Knock Monitor to let us know what is happening.
Do the PCM 555 computers on 700sci's have knock sensors/knock sensor output available somehow, that can be tapped into/monitored on dash EASILY?
(Standard answer "it is a funny thing to know when it is SIGNIFICANT" not helpful)...if Mercury has algorithm it is using to cut spark/add fuel on what MERCURY considers "significant knock", we simply want to KNOW this, via a monitor not buried in screens someplace or having to manually look for "fault codes" buried in SmartCraft screens.
Thanks!

J&S Electronics SafeGuard Indivdual Cylinder Knock Control

Mercury can reflash your stock PCM to run on 89. Uses more fuel though. Had mine done for REC90 in Florida.

Just FYI, I spoke with Mercury Racing today. They "think" they can reflash to 89. Chris said it's been a long time since they have done the reflash, and they would have to make sure they had everything lined up before he could commit. The PCMs would have to be sent it through a Merc dealer.