318 wont rev above 5,300

What are your spark plugs Brand/Range...and what are they gapped to? Boost tends to BLOW the spark out under High Load situations.
I recommend nothing but NGK Copper Plugs.

If your plugs are gapped like stock specs....close them up to .028 and report back.

I agree with everyone else....you need less Final Drive Ratio to fully load that bad boy on the big end....mmm SG 3.23's

Good luck.