Example: roids. Used appropriately, they can help improve your body.
Correction: they can improve aspects of your body, at a very, very steep cost. Pretty much all oral anabolic steroids are C17α-alkylated, and they’re hepatotoxic (i.e., cause liver damage). All steroids will fuck up your lipid profile to one degree or another, and all of them can cause heart disease, specifically hypertrophic cardiomyopathy. While most AASs will increase red blood cell count, Boldenone in particular will sharply increase RBC production, which in turn increases blood pressure and can cause strokes. All of them will shut down the hypothalmus-pituitary-testicular axis (HPTA) feedback loop in men, leading to testicular atrophy. Most AASs will cause hair loss in men that are sensitive to DHT. AASs can fuck up your hormones enough that men can start lactating (!!!). High doses of testosterone can cause gynecomastia, because testosterone aromatizes into estradiol. In women, all AAS will cause some degree of virilization.
There are not very many IFBB pros that make it to 80; if you want your candle to burn brightly, it’s going to burn out fast.
Depends on the application. A dirt bike? Absolutely not; too much torque and horsepower means that you’re going to spin your wheel regularly (and this is why most dirt bikes are thumpers, too). A conventional street bike, touring, or dual sport? You can probably go a little lower, but probably not a lot for a large touring bike like a Gold Wing. A sport bike? That’s low, by at least 20bhp; 100-ish bhp is about the lowest you’ll see for a 600cc-class sport bike. I can’t say for certain what the tops competitive 1000cc supersport bikes are putting out, but it’s probably close to 200bhp. And all of that power needs to be in a very light package, because you need the maneuverability to quickly negotiate s-curves. (I live in the mountains; there are a number of s-curves near where I live. I’ve seen the aftermath of cruisers crashing because they misjudged corner speeds.)