To the original poster the there are only few different parts between the original impact and the Mk2
barrel can now have different liners twist rates ,new system will fit mk1
larger magazine,ok for target but Imo pointless when hunting ,new system will fit mk1
larger gauges ,new ones will fit mk1
larger regulator ,not really necessary
larger plenum ,probably get swapped for the new power plenum anyway more power more shots less air .
the reason I like mine is they are so flexible If you like to tinker and change this you will love the impact
mick