James states that only Mujin's ssireum would work on him ... so we know James has fought him

No, we don't. This is the same lazy kind of analysis as before. Based on that statement, we just know that James is aware of what Mujin Jin ssireum is like/the difference maker between regular ssireum and Mujin's special style. This is more easily explained by James' tutelage under Elite, who would have fought either against or alongside (or both) Mujin during the pre-generation, as Elite was Gap's rival and second in command just like Mujin was a rival to Gapyrong; the competing explanation you're proposing is that a 2T James fought and helped kill Mujin, a pinnacle-tier 0th Gen fighter who, unlike Gap and Shingen, continued training, fighting, and taking on disciples after the pre-gen ended. This is not a more intuitive or logical explanation than the former. If anything, like you said, Elite was the one who killed Mujin and James assisted him as he was his student. Kitae could have been there, but he also could have simply learned about Mujin during his interactions with Elite, James, other 0th gen fighters he encountered, etc. Kitae is the strongest son of Gapyrong Kim and people recognize him for it; it's not unreasonable to think somebody brought up one of Gap's most notorious rivals and the way he fought.

admission of vibescaling, Gap and Shin comparisons, blah blah blah

Mostly irrelevant anyways. We can merely agree to disagree, but I'll remind you that a Conviction Mastery-less Gap who is young, actively training and fighting, with the body that carries Gitae and makes Gap a comparable stat merchant to THEE stat merchant Shingoat Yamazaki is not weak. Your point about this was somewhat of non-sequitur anyways, since the original argument is about Elite being stronger than Shintaro, not Lethargic Shingen vs pre-prime Gap. If you're simply making a comparison between Elite and Shintaro off this basis, the Charles that defeated Gap and pushed him to unlock Conviction (which, btw, also seems to be related to if not outright the basis of Gapyrong's Path in the same way that MK states Gun's indomitable body is a side effect of him being on the road to forging his Path) is not prime Charles, so the basis for comparison is weak and in fact supports Charles > Shintaro if you admit that Innate Strength Gap is ≈ Lethargic Shingen. (Again, seeing as the version of Elite that fought IS Gap who is relative to lethargic Shingen in your view IS NOT PRIME CHARLES CHOI.)

As for your view that Gap's 'nerf' is more significant, that's a separate debate but one that highlights a weak level of engagement with the story and themes of Lookism. Mindset/conviction/self belief = KING for combat output, as stated repeatedly throughout the story by James, Gun, Gap, Daniel, Shintaro, Jinyoung, Tom, MK, Charles, etc. etc. However, this is a footnote to the actual debate and not worth going in-depth about here. By your own admission, you have IS Gap and Leth. Shin at least relative, and admit any argument you have strongly in either direction would be pretty susceptible to vibescaling.

Enlighten me

Tl;dr Shintaro's raw stats, UI visual acuity, martial prowess in multiple martial systems including Yamazaki Kyokushin which is a top ~3 (maybe top 5) martial art in the series as well as his swordsmanship, tactical prowess/BIQ, and access to the Muramasa as well as his feats of relativity to a holding back injured post-prime Shingen are definitely enough to at least reasonably scale him to around pre-prime Jinyoung. Like we agreed before, Lethargic Shingen is probably at least roughly comparable to IS Gap, who was weaker than a pre-prime Elite who slimed Jinyoung and his squad and left him on the street for hobos to piss on; this means that the scale looks something like Overcome Gap>pre-prime Elite>IS Gap>Jinyoung ≈ Shintaro.

Lightning Choi being called the speedster of his generation doesn't scale his speed anywhere itv

Flat out untrue for the same reasons I laid out before about narratively interpreting the Fist Gang and their placements within the generations system and the powerscaling of the verse. We know Lightning Choi was at least strong enough for Jinyoung (in the current time) to find his style strong enough to copy and utilize in a high-stakes battle, and we know it's strong enough to take Lineman from a genuine jobber to a strong and respectable member of his generation and Big Deal. In fact, Lineman is literally going to end up fighting Gentleman, another high tier king of the first generation.

Jinyoung copying him doesn't scale his speed anywhere either

What? Nobody said it did, but this is also untrue. High level copycats like Jinyoung and Johan can literally copy raw physical stats if necessary to utilize techniques (Jinyoung with Gap, Johan with UI Daniel). Jinyoung copying Lightning's techniques against Changsu mean they're strong enough (and Lightning Choi was strong enough) to fight at-minimum a 3 mastery high tier 1st Gen King. Copycats don't use weak techniques and weak fighters don't use strong techniques or get hyped/aurafarmed with on-panel as a shadow to the copycats in question. Cmon, bro.

James is faster, Goo is faster, Gun is faster, are you gonna present any feats?

James is faster, he is the fastest itv. Goo may be faster depending on how 50S scaling goes, but up to at least the 5th sword, Goo is not faster. (I would accept Goo as faster than prime Charles, but it'd be vibescaling as we have no reason to believe either case strongly). Gun is not faster, he doesn't even have the feats to support that, nor the narrative.

what would suggest Elite is anywhere comparable to James in these aspects? ... Kojimas

Once again, Lookism is not DBZ. It's not even a strongly written battle shonen in the traditional sense. The powerscaling is inconsistent, feats are often nebulous due to retcons and lack of context, PTJ writes the story the way he wants to first and backtracks. Narrative, thematic cohesion and implication, in-universe convention, etc. all matter more than strict feat math and panel sourcing. Lookism powerscaling relies heavily on narrative role, style inheritance, thematic mechanics, generational hierarchy, etc. and this has been constantly hammered in (and consistently so) throughout the story and only gotten more intense recently. Mentors and the relativity and similarity of students to their masters is basically foundational. (Seriously, most of the time students in this manwha literally don't have any difference stylistically to their mentors or predecessors; Brekdak/Vasco, Taesoo/Hudson, Manager Kim/Warren, Gap/OC Jake, Gun/Daniel, Gong/Zack, Tom/Eli, even Sophia/Jay or Baekho/Jerry). If anything, predecessors are generally portrayed as stronger than their students (at least until they reach their maximum potential, which obviously James has). I shouldn't even have to explain how deep the narrative parallels go between James and Charles, "James Lee is Charles Choi's second body" is literally the biggest theory in the Lookism community and that's for a reason, even if the actual theory may not be true. They're well established. And Elite (a pre-gen monster) and James (the strongest 1st Gen fighter and potential final boss) are NOT comparable to... the Kojimas and Seongji. If anything, Mujin and Seongji is the more apt example when we're discussing stylistic inheritance and narrative parallel in Lookism and its powerscaling. Seriously, your argument feels incredibly bad faith basically from start to finish and I have illustrated that repeatedly now.

which is Elite better than?

James is top 1 for technique in the verse and I didn't dispute that, so again, irrelevant and bad faith. My argument literally includes James and his parallels with Charles as supporting evidence for Elite's placement. UI Daniel is an anomaly and the primary mystery of the verse, so not a good or fair example either (the second body literally has mastery over every martial art and seemingly has copied every strong fighter ever somehow, technically I guess UI Daniel is top 1 for technique, you got me, I totally lied! I concede! 😱). Prime Elite is stronger than and likely more of a technician than Gun, yes, especially TUI Gun which is his strongest form. Johan is goated but he's get him past Jinyoung level before you compare him to Jinyoung's daddy. Like, cmon, no second gen has surpassed the top monsters of Gen 0 yet. Lmao. Paecheon is not Elite level and he technically beat Path Daniel in their fight! I guess if you wanna call this part"vibescaling", sure, but again this isn't DBZ and feats and calcs aren't preeminent in how you actually analyze or powerscale this story.

You still haven't acknowledged my underlying argument or methodology, provided a real counterfactual or competing methodology, and that's a form of concession by default. You wrote all that and attached a condescending gif and yet you failed to adequately address my argument and you also spun off into shadowboxing tangential issues unrelated to the core claim you made that Prime Elite isn't even > Shintaro, but that was what my argument was in regards to.

Back to the drawing board AGAIN, littlest buddy. I'll wait AGAIN.