My Pearl makes a lot of noise when she's going in the litterbox too and at first I was also concerned because it sounded like she was in pain. Luckily this is not the case and it's just part of her meezer personality. She has to alert everyone that she's using the litterbox. This may also be the case with Paris.

Symptoms of UTI/FUS:
A plugged cat will often exhibit these symptoms:

Frequent attempts to urinate; the cat is constantly scratching in and around the litter box
Small amounts of urine (wet spots in the litter box are small)
Straining; the cat spends lots of nonproductive time hunched over in the litter box
Painful urination; the cat may cry whenever he eliminates
Blood in urine; you may sometime see blood in the urine spots, but sometimes the blood can be seen only with a microscope
Inappropriate urination; the cat urinates in unusual places, such as on the floor, the couch, or your pillow

I hope that Paris is just a big talker and isn't in any pain while using the litterbox.