The turret is currently 2 S3 guns, but the original call out was for an S6 mount, which I believe ought to be able to hold a pair of S4 in a turret. Maybe the nerfed it?
I still love the ship but it is so narrow use, I think especially now that the Sentinel frame is stealthed, it's a better choice for most applications.
What I really want are three large reactor housings in the Polaris that allow smaller reactors if wanted. If you could stealth the Polaris, there's far less reason for the Prowler.