Best M4 GTS rival street times, parts question

Hey guys,

So basically I’ve set myself with a goal of being the fastest M4 GTS driver in the game (I just like to set goals like that - and the M4 because I’m in the market for one IRL), and I’m new to forza horizon 4. I’m just starting to get the hang of tuning, but there’s this one M4 I’ve noticed being driven by Likelj1998 that is currently 15 seconds faster than me in Derwent and honestly it’s super impressive. I’ve raced his ghost and his car literally burns me off in 5 seconds, without having even turned a corner really. Is there any possible way in knowing what parts he may have chosen? He hasn’t shared any tunes. I’ve re-tuned my car maybe 15-20 times at this point and bought out the whole upgrade store.

Perhaps someone might know the most optimal set-up currently for road racing for the M4 GTS?

Cheers guys