On mine, I'm using Calkulin's E4GT ROM v2.8.1 and that's it. Before, I was using Calkulin's E4GT ROM v1.1 then added the lostexp+ kernel. To over clock, I was using CPU Master. I tried switching to Tegrak with the new setup, but that still wouldn't let me overclock to 1.6 on Calkulin's v2.8.1. I was able to overclock on v1.1, but not on v2.8.1.
Tegrak's max CPU step is 1.452ghz and is meant to be run with a stock kernel.
The ability to use higher CPU frequencies is set by the kernel, not the ROM. Since Calkulin's current ROM version is packaged with the stock EL29 kernel, the max CPU step is 1.2, which can be pushed a bit higher by Tegrak. You were able to overclock higher before with CPU Master because you were running the LoStKernel.
Flash the new custom Rogue kernel "Gunslinger" linked above which is based off the EL29 source code that was recently published, and you'll be able to use your old CPU app and hit 1.6 again.
Although, I wonder why you feel the need to overclock at all. I underclock my CPU to 1000 and undervolt each CPU step from 200 to 1000 by 75mV and the phone still cuts through everything with no lag or slow downs. The benefit obviously is superior battery life with equal performance.
But to each his own.