2000 Silverado ticking noise

have ticking noise, passenger side of 6.0L. Had it on my 99 also, dealer said to "drive it". No explanation... Can anyone help?
Also have K&N filter update, w/ flowmaster exhaust, has anyone noticed any increase in power/fuel mileage?
Thanks

piston slap is normal for those engines. unless you blow it up, you won't get much of an answer from gm. The only thing we can suggest is to run 15/40 oil in it, to try and take some of the noise away.