Great guide... helped me through. Thanks! If anyone else was struggling to find the last Gadget Bar Upgrade, its in A Penny Saved. Follow guide: "Once you do the computer hack, then slide down the two wires. There is a tower in the middle of the area that you will have to use your wheelbar to goto the top. Once at the top, break the window to get the Gadget Bar Upgrade," but you WILL NOT see it until you BREAK THE GLASS. You may not see the glass, so once you get to the top of the ladder, just start swinging. Once the glass breaks, the Upgrade will appear.
I am off to try for a 30 hit combo!