krank rev jr

I'm loving the sound of that. I think I need an SD-1.
I just got my Rev. Jr. today.
I'm running

Hellraiser C-1 (EMG 81) > POD XT > Rev. Jr > Carvin 2x12/Krank 1x12

I'm experimenting with the POD both pre and in the effects loop, but I'm going to sell it and get something
with true bypass. Can anyone recommend a great pedal for this amp?

Get rid of the POD all together, just run straight into the Krank then into the 1x12 with these settings.

Sweep: 8
Bass: 4
Mids: 4
Highs: 7
Gain: 7 Boost on

Try that.

When I had mine I also used the SD-1 with it instead of the Tube Screamer
 
Is the boost just a straight up gain boost on these amps or does it also have some kind of effect on the tone?
 
The boost does give it a slightly different tone, but I think it's mostly just a gain boost.

I found a nice 4x12 to run mine through. Comes with a Laney AOR 100.
I'm hopefully buying it with the money I got from the Carvin.
Hope I get it!

What kind of sound can I expect from my Krank with a 4x12 with Celestion G12M 70's?
Will it give me the low end I want?