Re: pedal moding people!
Can't say for sure but I think the 1N4004's have a higher voltage threshold so that may make the pedal a little louder vs. 1N4001's. Wouldn't hurt to try them so long as the leads fit through the PCB.
As for caps, I've been using the red Panasonic film caps. Low noise, small footprint, and cheap. Which reminds me, I need to order some soon. If you can't get the Panasonics, any film cap will do the trick.
I thought I left out the diode swaps on my page but they're there near the bottom, and I didn't change D6, just D4 & D5.