Obviously you may end up voiding warranties, losing on-going support
from the manufacturer, or there may be a contract you agreed to
stating that you won't do it, but assuming none of that is relevant
(e.g. a salvaged Tesla doesn't get support/warranty anyway) is there
any law preventing you from modifying your property to remove the
limits placed on it?
This assumes away one of the biggest issues, which is doing this is almost certainly a breach of contract unless the contract term is void as against public policy (which it probably isn't). So, the manufacturer can sue you for money damages probably equal to the difference in value between the limited and unlimited hardware in the marketplace. The manufacturer might also be able to obtain an injunction against this practice, which could result in the incarceration of someone who knowingly violated this court order for contempt of court, once an injunction is secured from a court to enforce the contract.
There is also an anti-hacking statute in the United States, whose plain language appears to prohibit taking actions that override a digital system's security features. Unlocking these hardware features would appear to violate this statute. This is part of the Digital Millennium Copyright Act (DMCA) and is codified at United States Code Title 17, Section 1201. As Wikipedia explains:
17 U.S.C. 1201 is often known as the DMCA anti-circumvention
provisions. These provisions changed the remedies for the
circumvention of copy-prevention systems (also called "technical
protection measures") and required that all analog video recorders
have support for a specific form of copy prevention created by
Macrovision (now Rovi Corporation) built in, giving Macrovision an
effective monopoly on the analog video-recording copy-prevention
market. The section contains a number of specific limitations and
exemptions, for such things as government research and reverse
engineering in specified situations. Although, section 1201(c) of the
title stated that the section does not change the underlying
substantive copyright infringement rights, remedies, or defenses, it
did not make those defenses available in circumvention actions. The
section does not include a fair use exemption from criminality nor a
scienter requirement, so criminal liability could attach to even
unintended circumvention for legitimate purposes.
The statute is quite lengthy and full of technical definitions and narrow exceptions and exceptions to exceptions to the general rule.
These legal issues have mostly gained media attention in the context of farmers who seek to hack into the built in software of their farm machinery in order to repair it where the manufacturing companies have not cooperated. There have been legislative fixes proposed that would make these prohibition void as against public policy for some specific purposes like doing repairs. There have also been efforts to characterize this kind of business practice as an anti-trust violation. But, none of that legislation has passed in the United States, to the best of my knowledge and belief.
But, I am not aware of any high profile legal precedent that has addressed this point but I wouldn't rule out the possibility that there is one. The closest case I could find on point (from the High Court in Australia) is Stevens v. Sony, which holds "that a device allowing PlayStations to play games with a different region code did not violate the anti-circumvention laws, because the mechanism in the PlayStation did not directly prevent the infringement of copyright."
I am not personally familiar with non-U.S. law on this topic. Wikipedia reviews some of the applicable law in the E.U. and Australia.
According to this Wikipedia entry, pursuant to European Directive 2001/29/EC of the European Parliament and of the council of May 22, 2001 on the harmonisation of certain aspects of copyright and related rights in the information society, E.U. member nations must adopt domestic anti-circumvention statutes that meet certain minimum E.U. standards set forth in the directive.
Also according to the same Wikipedia entry: "Australia prohibits circumvention of "access control technical protection measures" in Section 116 of the Copyright Act." In Australia, "Penalties for violation of the anti-circumvention laws include an injunction, monetary damages, and destruction of enabling devices."