TVIS Disconnect = MID RANGE GRUNT
There are really only a few free mods, add this one. Give it a shot, if you don't like it, switch it back!

On hearsay, we disconnected our TVIS to see what happened to the low end and midrange, and from SOTP testing, we maybe lost a little low end, but gained quite a bit of midrange where the TVIS used to switch over. Later gen J-SPEC motors got rid of TVIS all together, hmmmm. Remember to plug the hose with a screw.