Perhaps you are not understanding some nuances of 'superior performance'? You are unlikely to have ever shoe-horned a Turbo-charged V-8 into a Ford Pinto which certainly gives it 'superior performance' compared to other Pintos and allows it to compete with cars that would easily outperform its stock versions. And if your opponent came to the race expecting to compete against Pintos with 2L four cylinder engines...well he is in for a surprise. And yes, wholesale replacements of major systems is 'tinkering' to me.I thought quite a few times about what happens to older TL equipment in Traveller. Obsolete may have a different meaning on different worlds.
Also, its a myth that tinkering with old technology can produce a better capability. In general, a design would cost up to 200% to go through a redesign that changed its use requirement even 10%. This option is the least viable, and usually the last option taken when nothing else is available.
Cheers
Greg