Smashdrive not working properly?

[vendettav]

Hey guys so i built this
http://www.aronnelson.com/gallery/main.php/v/TheBigMan-Layouts/smashdrive.gif.html

and surprisingly it gave me quite a strange sound... two components i didnt have were the 100ohm resistor which was replaced with a 150 ohm one and the 0.0047 which i erplaced with some other stuff (messed a bit and i only got a more bassy and more trebly tone).. oh and the pot was 10k instead of 5k...
so i got this very nasty almost cotave up tone out of it when i'd turn the gain pot down... what is it??? like it was acting like a really fizzy fuzz and with an envelope filter a bit... am i having smoe errors or is it that im on the edge of a new pedal design??   

help