it's all about an individual's tolerance to each one of the drugs AND the combination. there's no way to say how your buddy will react with precision. i have friends who can take 100-150 mgs of adrol a day with a gram of test a week and get nothing more than a little acne and water retention, and others who take half a drol every other day and watch their hair fall out.
same with tren- some folks can use it with no problems (of course keeping the kidneys flushed with at least 2 galloons of water a day) while others take one shot and have lower back pain and brown urine.
is tren known to be hard on the kidneys? YES. is adrol tough on the liver? YES. is test suppressive on the body's own hormone production? YES. however, the extent to which your buddy will be affected by these sides (and others) can only be determined by careful administration and observation.
he should start with a low dose of each drug and monitor how he feels. follow the typical modus operandi while on, and if he feels ok increase the dosage. monitor. test. if he begins to feel bad then he should simply cut out one or more of the drugs.