MRI grade vs Hospital grade electric outlets

I know both have been suggested as an upgrade to the run of the mill cheap outlets. I also know there may be "even better" outlets.   I know the MRI grade has non magnetic metal components. Bottom line, does it make a difference one can hear? I have about 1/2 dozen Hubbell 30 Watt hospital grade outlets. Got them fairly inexpensively. Are the MRI grade worth the extra $$$?
I just got the Porter Ports wired to the outlet for my system and I a bit puzzled as I honestly expected zero improvement.  I have called BS on the "fuse-heads" and a boatload of other tweaks I have tried and rejected.  While my impressions are purely subjective, I am apt to concede that familiar music has taken on a bit more vividness and the LF seems a bit more impactful.  The music just seems a bit more alive, with a greater degree of clarity.  In contrast to other folks in this thread, it is nowhere close to upgrading my amplifier.  Still, viscerally, I am liking what I am hearing and the $80 investment for two PP outlets strikes me as a fair price for a tweak.  

At any rate, the PP outlets do grab my canted heavy power cords with far more authority than the outlets they replaced.  A cheaper route would be to upgrade your basic AC receptacles to the standard non-cry-treated Hubbell 5362 receptacles, which is what the PP outlets are, and if you get an improvement in sound, that will be dandy, but for sure you will have a much more secure connection for your power cords.  Cheers, Whitestix 
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I hope I don’t confuse things more. I began Porter Ports many years ago here at Audiogon as a personal project when I rewired my homes electrical to benefit my audio system.

I tried several brands and designs of outlets and preferred the Hubbell 20 Amp hospital grade and posted results about it here. People said they wanted a few for themselves and I agreed if I could get a bunch of people together and cryo treat 25 or 50 of them I would do that.

I delivered the first batch and assumed that would be that. Everyone was happy and ask for more. This was back in 2001, 16 years ago I never imagined it would go on this long.

Then as with all good things, Hubbell began making changes, some to cut cost and some to (supposedly) conform to government rules.

Basically, I can no longer get Hospital grade without the plating. So I worked a deal with Hubbell to deliver 5362 with (non plated) Hospital grade interior parts, heavy 5362 body and unplated back strap. I sold these for the past few years, all the while hoping Hubbell would return to production of alternate unplated outlets such as the original Hospital grade. So far they have not seen fit to do so.

Fast forward to the past few months, several people claim the IG (isolated ground) version of Hubbell sounds better. I do not hear a difference in my system but I have plastic boxes in my walls so Hospital grade (yes I still have some in my system) and the new 5362, both perform same as an IG design since the grounds of these outlets cannot share in a non conductive plastic box.

So just to cover all bases I am now ordering Hubbell to build IG version with no plating and that’s what I have in stock, probably 500 or so at the moment. With more on the way. So regardless if a person has plastic outlets or metal they should have same performance.

In any case there have been at least eight price increases since I began selling these 16 years ago here at Audiogon. With sales volume increasing every year I keep working better deals from Hubbell, buying as many as a couple of thousand at a time to keep sales price low.

I kept it at $36.00 until recently, even after all the price increases by Hubbell, cost of shipping, increase in price of cryo treatment and cost of ads here at Audiogon I am still charging only $41.00. A $5.00 increase in price over 16 years is not bad considering what everything else has done.

I have lots of people using them including two reviewers at Absolute Sound, a couple of recording studios and hundreds of Audiogon members. Most folks think they are an improvement and a good value.

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I agree that they are an improvement (slight but noticeable) in sound over standard wall outlets.  But unfortunately they do not have a strong enough grip on heavier gauge power cables.  I have been using two for the past couple years and must hang my plugs that go into the porter ports with heavy rubber bands hung over a screw in the wall above them.  I also have two PS Audio power ports.  No issue with grip on them as they as super tight fitting.  And I can tell no difference in sound between them.  So if you are thinking about buying the Porter ports and are using heavier power cables like my Pangeas 9SE, be prepared to provide additional support for them due to their rather sloppy grip.