Bad tune, or engine at its limit?

[Dirtybob]

Did you tune that with a dyno, or have you tweaked it with trial and error at the track?

I baselined it with the butt dyno and then finished tuning at the dragstrip.
I saw more kr on the street than at the track (varying conditions vs. WOT all the time). Going from light throttle cruising in 3rd gear around 50 mph to full throttle downshift (into 2nd) will still carry a bit of kr beyond burst knock - sometimes. Was able to run timing up to 35 deg with 93 octane and no (WOT) kr, ran the same ET/mph/60' as 30 deg advance on 10% ethanol 87 octane (also kr free). Car is a daily driver so cheap gas is a bonus. Worth mentioning that w/e pos opti I have is probably not indexed correctly from the mfr. - there are some timing light discrepancies. I quit worrying about it and just tuned it for what it wants. Small amounts of kr had no effect on ET/mph/60' but I tuned it kr free to be safe. Progressively leaned out PE afr as far as 13.5:1, sweet spot appeared to be about 13.1:1.
stock 178k mile motor '95 Roadmaster, 3.42s/posi, ebay headers. 4450# as driven. 14.66 @ 92.5 - 2.045 60', 1800' DA. Needs more power (and a diet lol) plus a real (not a 12") torque converter...
http://magic-photos.com/2011/Fri%20F...s/DSC_0306.JPG

I would say if you can't hear it rattle (assuming your car isn't obnoxious loud), and the knock counts are minimal, you are at low risk to hurt anything. Have you tried higher octane to see if kr is reduced?

Edit: headers will amplify valvetrain noise - but you probably already know that...