Recently put pacesetter long tubes, y pipe, comp cams xr265hr cam, ls6 valve springs in my 5.3 sierra z71 4x4. Rebuilt the 4l60e with the transgo hd2 shift kit, vette servo and trailblazer converter. Had a local shop street tune it and it runs good but still seems like it's holding back. I have 20" silverado ss wheels with 275/55/20 cooper zeon tires. It has the gt4 3.73 gears. My thoughts were find a wrecked truck with 4.10's and swap the axles but will that be enough? I could go 4.56 and would cost alot more but would it be worth it? I was thinking maybe I needed a higher stall converter since the tb stalls around 2200 but even at highway speeds and higher rpms it seems like it's holding back. Any suggestions?