The TC3 diffs can be adjusted in the car, you just have to pop the one tire off and insert the driver into the hex and rotate the opposite side tire to tighten or loosen....
Thanks for the help with the setup, makes sense to me...I tried the front spool last year (was one of the first people to have the IRS version, Dave Irragang is a local) and it worked real well, except I seemed to get swirly coming out of the corners on power, it is broke the front wheels loose....I did get it better by end of the outdoor season though....I went stiffer on my front spings and increased oil weight....