The GI Fuzz is one of my favourite fuzz pedals, but it's not that bass friendly. It cuts through well when set right.
And versatile.
You may need a blender for it.
The GI does tend to lose a bit of low end. With the tone turned all the way down it's not too bad, but it's not really voiced for bass guitar, especially if you play a 5'er.
I use mine with a blender (
VB-Jr) and invert the phase to get back the lows nice and FAT.
Play with the "bias" knob, produce a brown note.

But it's definitely one of those
"try-before-you-buy" pedals, it's so rough that it's not for everyone......
The Neo is worth a look too - more bass friendly than the GI.