I can personally attest that STI booster/master improved brake feel. Of course I installed s/s lines, stoptech pads and new slotted rotors. Car stops on a dime now, there's no guessing if it will stop in time in panic stop.
just installed it on our 05LGT. Brake feel is more consistent, no more "dead spot" at the top of pedal. Definitely improved feel. I can imagine it would be even better with some slotted rotors and decent brake pads.
what about using this check valve
http://www.oreillyauto.com/site/c/detail/DOR3/80189/N0284.oap?ck=Search_check+valve_1430731_2924&keyword=check+valve
http://images.oreillyauto.com/parts/img/medium/dor/80189-001.jpg
http://www.oreillyauto.com/site/c/detail/DOR3/80189/N0284.oap?ck=Search_check+valve_1430731_2924&keyword=check+valve#
Just got 2 gallons of Shell Rotella 5w-40. I asked sales clerk if they have any 1qts and he said they pulled qts off the shelves and sent back. I wonder why???