Swapped in my B16b and I already had this CTR cluster on hand with a top speed of 180kmh. Was testing this bad boy out and realized I was in 5th gear @5600 RPMS and was already topped out @180kmh, and when I try to push it past that the engine chokes and dials down to about 160kmh. Keep in mind my redline is set @8200 RPMs and my vtec kicks in @6200 RPMs. My buddy told me I just need to replace the cluster with an Si cluster and that should do it, but don't I need to tune it after or can I just keep the CTR cluster and tune it to go past the 180kmh?

I would suggest trying a different cluster before buying the si.

This youtube video tells a different picture, your cluster should work. Could be ecu related.

What ecu are you currently using?