Hakujin

I am thinking about purchasing a tuning kit for my 98 SLK230, however I have a question about what adding this much horsepower to my car will do to the OE parts already on the car. (I saw a kit from brabus that would make the car 250hp) I'm obviously not an engineer, but to me it seems the engine/transmission is made to run at a certain horsewpower and under certain conditions. Doesn't installing a tuning kit, adding more air intake, or changing pullys decrease the life of the other original parts? (I want my street legal go cart to go faster, but I'm not willing to do it if everything is going to break apart in a few years)

Any advice on this would be most appreciated.