OD-3 bass reduction help...

[CoolJohnny]

checked out some of the various mods out there to make this overdrive sound a bit less wooly (that's really the only complaint i have with it). sadly i just kind of attacked it without much thought to the bypassed signal. now overdrive sounds great but its affecting everything i put before it and after it in weird ways. for example if i put another drive before it with the OD-3 bypassed it comes out really trebly, after the OD-3 i get a serious volume drop. did i do the wrong mods? what should i change back to stock to a avoid this problem? all help much appreciated...