Give me the Bio Facts :P I would assume all legitimate clinics would doing contraband and security scans of deposited morphs. For an ego being aware of unrequested implants a lot of that will be determined if it is wired into the somatic or automatic nervous system and as an example i am-not physically aware of every muscle in my body and if it was not for a basic knowledge of antinomy i would not know it to be there. however if a person is going between very different morph types there is a chance for discover since there would be an acclimatization periods before your mind desensitizes to the numerous strange inputs

I think you could get away with a lot. When a car dealer gets a car from a trusted supplier, they're hardly going to look at it. If they get it from a private seller, it's going to get more of a check but still unlikely to be anything that would detect malicious, skilled tampering. Even if you do a complete scan, a standard morph with standard components can get compared to blueprints and detect anomalies, but anything non-standard is going to take many manhours to identify as malicious. Imagine you open up a computer and find hardware you're not familiar with - figuring out what does what at the level needed to identify tampering is not going to be easy. Of course, some implants will show up on an x-ray or MRI scan, but others will just be very hard to tell apart from legitimate mods. The only difference might even be in software. Not to mention modifying the morph after they check it. Plenty of room for hackers, infiltrators and social engineers to mess with the supply line or storage and get away with it. Bottom line is, good security is difficult. Most people won't care much and rely on their unimportance as their main defense. The more security conscious could rely on measures like trusted sources, drawing a random morph from storage at the last minute so the opposition can't target a single one, insisting on no custom mods that can't be checked and verified, replacing mesh inserts when sleeving, more thorough checks in a healing vat and skilled technicians analysing everything, etc. So i think that Joe Average (or a covert team that has to act like him) is very easy to set up with a secret implant. A VIP, not so much.

In short: I think you're right that hiding an implant from a morph who is looking for it and has access to medical facilities is probably hard, but my default assumption isn't that doctors or the healing vat are going to actively look for or call attention to implants. I think for just a healing vat it would make sense that (a) the vat detects and repairs the module(s) as appropriate but (b) doesn't consider this "interesting" and therefore doesn't alert anyone. And it should only find the implant if it has to repair it. For someone receiving care from people, and depending on the implant, I think calling for some sort of medical check to notice the out of place implant makes sense, with implant masking giving -30 to that check. Given the huge range of custom implants and custom morphs I'm willing to believe that a Ghostrider can be mocked up to look (upon casual inspection) like something else. It might even be as simple as most implants broadcasting what they are and most medical professionals and devices accepting that claim. The ghostrider can be tagged as part of the standard cortical stack etc.