As a pervious Sportline splitter owner, that's just a bad angle to take the photo, and they don't look that exaggerated in real life
Silver is a hard colour to make that splitter blend in better, but I found my Black T6 looked much better with wider front wheels. This moved the tyre edge level with the end of the splitter and made it look less bulbous. I think fitting Black arch extensions to a Silver T6, butting up to a Silver splitter will look a little odd, and might make the splitter stand out even more.
I don't dislike the Sportline splitter, it just takes some tweaking to get the look right.
Have you tried putting spacers on the wheels?