After reading another thread on the GT-500, I found out that Fulltone has made some mods to the GT already. I contacted axe2grind who did some of the mods, and was given the Fulltone pdf by Rod. Thanks to both of you for the information! There are four mods: #1--lessen compression in distortion (most all GT's already have this). #2--smoothen distortion (pre-gain treble reduction I believe) #3--"Highs" control mod to reduce treble #4--bass reduction for boost My GT is #62 and was once sent in to Fulltone for a bad Dist. volume pot. When I checked the mods, I noticed that mine already had the input mod (#1). I haven't done mod #3 (highs control mod), and have no need for the boost mod. I spent all my time experimenting with mod #2, which I believe affects the pre-distortion treble (someone in the know correct me if I am wrong). I used some alligator clamps to quickly change different value caps. 330pf (per the mod) was pretty subtle, though it did take away a little harshness. I found that it sounded better, but couldn't really put my finger on it. 470pf made a noticeable difference in the harshness, but didn't really change the way the drive felt too much. It stayed pretty clear. At 1nf, the pedal became very creamy sounding. It was like the distortion channel went from JCM800 to JTM45. I liked it through my '65 Princeton, but felt it might be a shade too dark with my TopHats. In addition, it came a lot closer to some of my other overdrives in tone. I finally settled on the 470pf and hope it will be the perfect compromise as I test it the next few weeks. I am pretty sure it will stay. I will probably update this thread myself after some time testing. I hope it will be useful for anyone who is almost really happy with the GT. If anyone can contribute info on the other mods, please post it for the community. Now if could only mod the ugly gray paint job--how boring!