The Smiter
Although there will be several other PPruners who may have actually flown in PA1 (MRA4), I had the pleasure of actually seeing the method of egress devised for it.
It consists of a upwardly sliding, heavily sprung door which together with a barrier forced out into the airflow, is activated by a handle. This applies to the forward and rear starboard doors, and the barrier is supposed to give the opportunity to get some downward direction before being wisked past the rather large engine intakes or horizontal tail planes.
I think I would prefer to dive out and downwards, if I had ever been in the unenviable position of having to get out using a parachute, as the possibility of decapitating myself seemed all to real from where I was looking.
Someone will probably be along shortly, who has flown in PA1 to either confirm or deny my impressions.