Modding pedals for bass

[Triple Pole]

Hi all

I have a friend who likes the couple of pedals Ive made from circuits on here. He asked me to build him a distortion  but he plays bass. Is there a standard way of modding circuits so they cover the frequencies of the bass. I had assumed that distortions would work with what ever you put in there but off course it would have to be a bassy one.

If anyone can tell me how to mod a pedal for basss or even suggest a guitar pedal that has enough bass balls to work for my friend, I would be very greatful..

Cheers
Pat (Noob btw)