Originally Posted by PaoloJM

A "choke" is an inductor. It has a low DC resistance and a high AC impedance.
A choke mod replaces the standard power resistor that some amps use.
The result of this is a more stable/solid screen and preamp voltage and much less sagging. The resistor will cause a voltage drop proportional to the current through it, this is what causes the sag while you play. The choke will not do this.
This results in a much tighter sound, and is great for modern rock.
I find the sag of the power resistor works really well for blues and classic rock.

The high AC impedance of the choke also reduces the buzz when playing at high gain levels.

The 900 would benefit from this mod if you play more modern, heavier rock/metal.

Originally Posted by steelhorse

I couldn't handle it after a few minutes. I got whiplash during the cleans (from almost nodding off) and then thought the dog was howling during the first part of the distortion.

He pretty much lost me with the tongue thing right off the bat though to be honest.