Ok need a little help here
 

Allright I've got a 350 40 over with a factory lt4 cam stock vortec heads tes headers and a stealth ram my base timing is set at 8 degrees and fuel pressure to 50 psi with the vacume plugged.

Before it would scream up to 6500 rpm then I took my cat back off to make way (I have a set of super comps and 4 inch mufflex waiting to go on) and of course drove it around on the open y pipe now above 5000 under load it chuggs and sputters.

I thought it might be knocking and pulling timing but wouldent that throw a code?

Any feed back is greatly appreciated.

AL