It involves making a bypass for heated coolant (hows that for an oxymoron) around the throttle body. GM designed the throttle body to get the heated coolant so that the throttle body wouldn't ice up in sub zero weather. Heating the TB results in a hotter intake air temperature which results in slightly less horse power.
I wish this mod gave 100 rwhp: it actually only gives 3 or so. But, its free horsepower; 3 more than you had, anyway. The vast majority of places in the US don't have to worry about such low temps and even in those places the risk of TB icing is slight.
The mod is pretty easy. There are two rubber hoses coming out of the bottom sides of the TB: the one on the drivers side goes to a metal pipe coming of the engine heads, the one on the passenger side of the TB goes to the radiator. Essentially, you take the rubber hose from the passenger side of the TB and put it on the metal pipe coming from the engine (you also have to remove the short hose from the metal pipe to the drivers side of the TB). This takes the TB out of the coolant loop. As stated in the first post, you have to trim the radiator side hose a little because its too long when run to metal pipe. After a while (few days) the coolant path in the TB will have dried out and then you can put vacumn caps on the TB where the hoses had attached, to keep dirt out.
2004 Pulse Red GTO M6 - New Era CAI, TB Bypass, CAGS, Custom Split Exhaust, SLP Sway Bar & Bushings, BMR Strut Brace, HID, Sans Spoiler, Sirius
2002 Quicksilver Z06 - A Few Upgrades