hi mate,
i had a pro-system on mine and it wasnt spectacular. i dont know what the slimtechs are like.
what i did was take mine to sandwell field sports and had a full length shroud fitted.they chop the barrel an inch or two before hand so you end up with a
gun thats about 43ins and looks and feels very good.
the down side is cost. remember for sure but i think it was about 80-90 quid. but well worth it imo...hth
regards shaun