There are all kinds of DS-1 mods out there and some are better than others. I've tried several and replaced all caps, the IC, etc...but it always falls short because of the overcompressed sound that plagues Boss distortion and OD pedals. I hit my low E string to hear the bass and when the stock DS-1 is engaged it cuts off so much low end it is ridiculous! This is why an old MIJ DS-1 is surprising because it is very open and warm. The reason is the diodes. The 1S2476 diodes clip at higher voltage in the circuit than the stock diodes in the new DS-1s or common diodes like the 1N4002. That is what opens up the tone to be very good. The 1S2476 diodes aren't in production anymore, but you can get a hold of older ones or try two diodes in series for each of the two clipping diodes to achieve the same result.
I modified a DS-1 and did put the 1S2476 diodes in as well. You can hear it in the link below: