Niacin can be used to help speed up the detox. Here is a link with more information regarding Niacin.

The role of niacin in detoxification
Niacin does nothing to help pass a U/A. That healingdaily link is just another perpetuation of the niacin myth. Nowhere in that article makes any specific references to THC. And if you notice in that link, theres references to L Ron Hubbard, the father of the Scientology movement. Hubbard was a crackpot who had absolutely no medical or biological training whatsoever, charges $20,000 to join his sect, advocates total silence during childbirth, and claims (along with his chief minions Tom Cruise and Brooke Sheilds) that niacin can cure anything from post-partum depression to toxic shock syndrome. He also claims that frequent pats to the forehead can rid ones mind of "demons" . Therefore, anything coming from Hubbard and his minionic believers should be taken with a box of salt.

Instead of placing any merit on regurgitated info stated by such absurd nutzos from the Scientology movement, further your research on how the human body processes THC.

Youd discover that THC is not toxic (therefore its incorrect to label THC a "toxin") and the rate limiting step of elimination is not the size of your blood vessels or whether or not they are dialated or constricted. The rate limiting step is the GFR (glomerular filtration rate) of the kidneys. GFR is the measurement of how much blood is filtered by the kidneys in one minute. A person's GFR remains relatively constant through a process called autoregulation, by which reflex changes in vascular tone inside the kidney help keep GFR constant despite daily fluctuations in blood pressure or cardiac output, such as with exercise.
I waked and baked this morning, then got a job offer a few hours ago. I raced out and got a Detoxify XXtra Clean 20oz and will be testing at home the day before, and morning of, the urine test. I need to call and schedule it, but the job wants me to start asap. I'm thinking Thur/Friday for the test, which will be about one week without THC.

In the meantime, I will be drinking oolong, chai and detox tea daily, as well as taking creatine monohydrate 700mg 3-4 times per day. I average a gallon of water per day this time of year.
Drinking water is only helpful on the day of the U/A. Drinking a bunch of water days before the U/A is of no help. It may cause frequent urination, but it has no effect on GFR.

All "detox" products are a total scam to seperate the credulous from their cash. You can spend upwards to $200 on a magic elixir, and accomplish nothing different that whats accomplished using just water and vitamin B2.

Read up on the Dilution sticky thread.

There is no product, nothing that can rid the body of THC. Only time and exercise can rid the body of THC.