what can cause a gsr to lag from 6k-8k rpm, my gsr lag on first gear, haven't taken it to second yet, but it lags from 6k-8k but low end is strong. i just did a head swap as well. could it be the valves are too tight?

 

Tight valves tend to affect the low RPM range. Did you connect the IAB on the manifold?

 

yes, i did, the iab is the little black box under the manifold right?

 

Do you hear it open at ~5750 RPM? It provides no feedback to the ECU, so a malfuntion would not trip a CEL.

 

check your timing with a timing gun if you just did a head swap

 

maybe the valve aren't seating why did you change the head?

 

timing is correct, change the head because my 2nd cylinder on my old head was only 130psi while the others are 190 psi, after the head change, all my cylinders are now 220 psi all across, so i'm not sure what it could be.