Tim, whoever told you that is a moron.

Dyno tuning your car is the safest thing you can do for it, next to not modding it at all.

With a custom dyno tune EVERY aspect of your cars usage will be improved, street and strip.

You'll get better gas milage, more power, and no knock, assuming all your supporting mods add up.

The only thing bad about dyno tuning is the price and the fact that if your car wasn't done properly beforehand, it could blow up *on* the dyno. But if that's the case, it would have done the same thing the first time you took it to the track or got on it hard on the street.