At what time stretching ratio would an audiophile notice a wrong pitch I have some low quality audio from my native tongue on a VHS. I am using this audio to dub HQ released of the same program (from another language source). The video frames/second ratio is 25:23.98 . I do not want to tamper with the fps ratio, since I am still using the other audio tracks as alternative languages in my video.

I can't notice a pitch difference from this conversion, I can only hear the pitch-changing VHS artefacts. 

Is a 25/23.98 ratio enough to need pitch correction? What is the rule of thumb? Would the VHS artefacts hide the pitch difference (too much pitch-noise to actually matter) or would the average pitch difference drive an audiophile up the wall?
Audiophiles don't hear anything unless they are told what to expect.

Joke aside, this is equivalent to transposition by a bit less than a semitone. The effect won't be noticed on voices - this is way too low for any kind "chipmunk" effect to be observed. As for music, some people very familiar with the original music might detect the change of tonality and/or tempo. But such stretching ratios are not unusual at all - DJs doing beat-matching, TV channels speeding up a sitcom to squeeze in more ads, and many, many movie to video conversions (telecine) have routinely used it.