I am not aware of any aftermarket ground-effects kits for the Buick Regal. However, all Buick Regal GS are equipped with subtle factory ground-effects. It would be possible to upgrade the appearance of a Buick Century using Regal GS ground-effects. The Century would look good with just the Regal GS side ground-effects, but it would be possible to do a Regal GS exterior conversion to a Century by also replacing the front/rear fascia, headlamps, and appropriate mounting frames/brackets if necessary. These parts can be found for the best prices at auto salvage yards. They can also be purchased brand new from any GM dealership.

This is a great looking, contemporary style custom rear wing sold and manufactured by Wings West that is specially designed for Buick Regal/Century. It is available in a lighted and unlighted version. The lighted version has a 15.5" LED brake light. Wings West, Part #591324L (w/LED light), 591324 (no light)

This rear wing is available in a lighted and unlighted version. Dawn Enterprises, Part No. REG-CEN (w/LED light), REG-E98 (no light)

Universal Wings
If you don't care for any of the above rear wings, you may want to choose a Universal one.