Boil a large pot of salted water, add the ziti pasta, and cook for about 8-10 minutes until al dente. Drain and rinse under cold water.

Finely dice the red onion, red bell pepper, and celery. Combine in a large bowl and sprinkle with celery salt, celery seed, and diced pimentos.

Grate the carrot and chop shreds further before adding to the bowl of vegetables. Mix well.

In a separate bowl, whisk together mayonnaise, sour cream, and white sugar until smooth. Adjust seasoning as needed.

Pour dressing into the bowl with vegetables and toss. Fold in the cooled pasta, ensuring an even coating.

Dice cheddar cheese and fold into the mixture.

Cover and chill in the fridge for 4-6 hours or overnight for best flavor.