I ordered my Impy form EPBO and it came with the LPR installed (on the ASA). You can get the new style ND Jackhammer II setup (the Jackhammer is really made by ANS, but New Desinz screwed it on an Impy valve cap) with the recessed valve cap for $105 US from them. It's comperable in price to the Respirator. If you have a vertical MaxFlo or a gas-thru with an ASA on your Imp you could just buy the Jackhammer and LPR nipple (about $85 US, I think) and mount it there instead of the valve cap (like mine).
This is my gun...
The other option is...
Hope this helps,
Jim.