tell your tuner to bump it up a notch, just a bit...........I'd say anywhere from 6500-6800 rpm is ok.............

 

What does the cam card say it's good for?
I would imagine your not getting much power past what the camshaft can produce.
IMO spinning it past that point is only increasing your chance of blowing a rod or crank - since it's a stock rotating assembly, and not fully balanced.

Every Gen 1 motor I ever built or had built, I was told 6K is about it, unless I look into balancing to allow for higher RPM safely. (Yea yea bla bla gen 3 is so much better - whatever - it's still reciprocating mass)

Don't get me wrong...Im all for extra horsepower, BUT, To me - the very little you'll get isn't worth the amount of damage you can do.

 

We always shift them stock at 6200, they feel like they fall off but they are just faster if you hold then longer. Id go 6500 for shur, that is safe still.