If you're entering modified, then the indicators will be fine

I've tried lots of Zymol stuff, and have been underwhelmed to be honest - i spent a lot of money on it, and got results either not as good, or at best only as good, as much cheaper products. Zymol Titanium actually lowered the quality of the finish on my FRST, and i had to redo the car with something else. This was back when Titanium wasn't available in this country too, and i imported it at great cost!

My advice for white would be:

Clearkote Vanilla Moose Glaze (this is your polish, ignore the name 'glaze'!)

Klasse All In One (this is your glaze/sealant, all in one, hence the name!)

Topped with multiple layers of Optimum Car Wax.

This would give a stunning finish on your S1, leaving you just with the need to then detail the non painted parts. As a bonus, Klasse AIO also works fantastically on silver wheels, so you could use it there too

Gareth