What is the difference between these two sentences:
" Yes, guys, I did say that."
“Yes, guys, I said that."
The difference is that 'did say' adds emphasis or confirmation, for example if the 'guys' had expressed doubt or surprise that you said that, or you had not been sure whether you had said it. Further emphasis could be provided by preceding 'did' with an adverb such as really, actually or definitely.