Anyone know what kind of horsepower I should exspect to gain. I just ordered a K&N filter for my 2003 z06 corvette?

Thanks....

From just changing to a K&N filter in the stock air induction system?

I've done back to back tests on a dyno and the increase is not measureable. I know K&N claims they are designed to increase HP but I've never seen them do that. Considering that going to a complete cold air inducation adds maybe 10 HP at the rear wheels, it would be a wonder if just changing the filter element alone would do anything.

If you are replacing a well used (partially clogged) filter with a brand new K&N, you get maybe 3-5 HP. But if you over-oil the K&N (most people do, it could be more restrictive than a new, really good stock brand, like Fram or Mr. Goodwrecnh supplied paper filter.