I used to worry all the time about which was worse: getting caught substituting or taking the chance. I have used substitution now so many times with synthetic urine that I feel more confident with that. It is so hard and nerve-wracking the first time but it has worked for me over the years and if you get the temp right and have the amount right (for me it is 50ml), once they seal it up you are good to go. In my situation if I ever leave a dilute specimen then they will next do an observed and then I am fucked. So to avoid a dilute and an observed I use synthetic. As I told you, it has never failed me but believe me I have been a nervous wreck at times. I got over that. I went to this website so many times before I made that choice and it was 2006 that I went for it and ever since I use synthetic. I never get results, no news is good news. I just know that if I don't hear anything within 48 hrs I am good. That is the way I live. You get used to it after a while. Trust me.