Ah, okay I am pretty satisfied that accuracy core has no options. As authentic as possible is fine by me haha.
Hmm, I have even tried unzipping the files and while mario kart runs, it still has weird glitches with the race track just a garbled mess.
I have the dsp files inside the game zip and in retroarch system folder and still garbled graphics
Last edit, I found that following the instructions to make dsp files with higan stand alone program.
If anyone needs help with dsp, take a look at this link. Thanks.