Ok heres a little background info on the DS-1 first
Well there's been 3 different versions of ds-1's:
The First ds-1's were made in Japan and inculded the Toshiba TA7136AP op-amp. This version was probably the best type of ds-1 you could buy, it had a very warm and mellow sound to it with plenty of crunch to it. You could buy these up until 1994.
Second Version was still made in Japan and it had the Rohm BA728N op-amp plus they removed about 5 components from the circuit. This version was very warm and mellow much like the previous version but it did have a bit more treble to it. This version was sold until 2000.
The final version is what we buy today. It's Made in Taiwan and it contains the Mitsubishi M5223AL op-amp and it has about a further 3 components removed from the circuit. This probably has the worst sound out of all the ds-1's its very bity and has too much treble and it sounds very thin.
Anyway modding any pedal WILL make it sound better unless you screw up and it dosen't work or you damage something inside the pedal. So normally when companies modify a ds-1 its normally the newest version and they try to give it a bit more bass and a bit more of a boost to it so that it will sound better and people will find it more useable.
Anyway heres and A/B test of a stock DS-1 compared to a Modified DS-1 so you can hear just how different they sound.
http://www.youtube.com/watch?v=nN2qoVkRRoI. Anyway hope that helped you.