Can I take cystex pills to pass a meth drug test if yes how many of them?

No. The color change that occurs with taking cystex would not have an impact on the test to detect amphetamines in your sample. However, the color change itself may be enough to have the testers more closely scrutinize you with other tests. Barring sudden and unanticipated reversal by the federal government of it's "war on drugs", the best option is to get help and get clean. Easier said than done.