Why mod? Are you not happy with what you're getting? Do you feel a mod would make a significant improvement?
TNJazz is spot on here. I've said it before, and I'll say it again. First, define the sonic characteristics you like and don't like about your gear. Next, try to identify which piece of gear and / or combation of gear accounts for the sonic characteristics you like and do not like. Finally, seek out gear that changes the sonic characteristics you don't like while attempting to preserve the ones you do like. It requires a fair amount of effort - recording, listening, repeat repeat repeat, listening to other recordings and gear combinations, etc. - but IMO it's the best way to change gear. I think a lot of people get caught up in "gotta have X because it'll sound better". Well, what does "better" mean? And at what cost? Each of us must decide on our own, and I think its best (well, for me anyway) to really listen and try to understand what I do or don't like and change accordingly (as others have also suggested in one form or another long before I got into the hobby). In other words, "use your ears" and "trust your ears".
Has anyone ever done an ABX with modded vs. unmodded gear? I wonder how drastic the difference really is.
I've done some self-noise and gain stage comparisons of a few pieces of gear, and published a couple here. I've also done some ABXing with stock v. modded gear, sometimes in ideal test conditions, other times not. In some cases, I found the mods stunningly better. In others, not so much. YMMV.