There is some evidence that aspirins interfere with the EMIT. Gatorade has the salts in it to keep your specific gravity up .

Some people swear by Certo, but others say it's just the water and dilution.

I took creatine for 2 weeks, and on the day of the test drank two large ice teas and about 32 ounces of gatorade, took vitamin B, and ate about 1000 mg of aspirins. Longtime smoker, 6' 225 lbs. Passed with flying colors. However, without dilution, I was coming up with very, very faint lines on the home dipstick after 45 days. Has a lot to do with your weight, metabolism, and how much/often/long you smoked.

For long-time, everyday smokers that aren't skinny and wirey, I'd say abstain for at least 45 days and use dilution. Substitution is still the best, but some of us don't like the hassle and taking the chance of getting caught.