Pretty good: OE Mudguards.
Good Mods: better tires, legal tint and clutch spring removal.
Great Mod: Clear bra! Bumper/Hood/Headlights.
Best Mod: Tow hitch. Now that it's a race car, it makes strapping it down in the trailer SUPER easier vs not having it.
Worst mod: None - I spent my 20's attaching garbage to my street cars - so I avoided that on my FRS.