New LS1 Owners - Newbie Tech - Just got 02 Z 40k miles has topend tick any body help?

Just baught a 02 Z28 when crank it up it has a topend tick to it for a sec. but then it quits and comes back at idle but i still went 8.50'S stock just a k&n. Is this normal is somthing bent :confused:

Thanks

It's called piston slap, it is normal for a lot of the LS1 cars. Nothing to worry about.