The workshop is going to add a pintle mounted stormbolter and a towing hook to the Exorcist for completion. Originally it was thought that given the role of this tank on the battle field a stormbolter would be a waste of effort but here is a paraphrased bit of advice from the GW site advice on the use of an Exorcist -
"A pintle mounted storm bolter adds very little to an Exorcist's firepower But, the way that the vehicle charts are organized, a tank is destroyed if all of its weapons are destroyed and it is subsequently immobilized. So the enemy has to destroy it as well to render your tank destroyed if it gets immobilized."
Survivability and the denial of scoring points makes the stormbolter a good idea. The towing hook will only add to its looks.