The shift kit permanently increases your line pressure via mechanical means. The faster shifts are a result of this increased line pressure. Reduced wear and less heat are side benefits since the internals do not slip against each other as much. To drive the car you wouldn't know it was kitted, just that it completes shifts a bit faster than other 4T65's.
Combined with the Dexron-VI ATF, you can barely tell the transmission is shifting aside from the engine note changing. Downshifts come faster, and torque converter shudder at highway speeds is cut down a lot.
For the grille block, here's how I did mine:
http://ecomodder.com/forum/showthrea...mmer-8836.html You can find thin-enough Lexan in Home Depot or Lowe's if you look in the roofing section. Otherwise a real hobby shop will have what you need.