You would have to ask Hyundai engineers, we don't build them.
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Hmm. So much for the DIESELS > MODIFICATIONS forum then.
All forum sections are initially created empty. The content that appears in these sections builds by the valued input of the forum members. If you can't find the answer to your question it's probably because no one has, or feels the need, to perform your modification. You could assist the other members by doing a little research and add to the knowledge base, rather than voice your frustration.
At a guess, I would say it is in the mapping as there are no gross mechanical variations between the engines.
Try using the search function & look for mapping, I know there are some people who advocate remapping rather than adding a simple "performance chip". Hope that helps a little.