Well, the removal/installation of the stickers all depends on what its on. I'm guess you put it on the windows for maximum gain right? If so, you've got a long couple of weeks to get it working right. The best thing to do is to just put the flowmasters back on so the sticker/muffler combo horsepower kicks back in. Otherwise, that flowmaster sticker and bassani exhaust is just gonna fight with each other and end up ruinign your clutch. This is all from personal expierence. If you are set on gettin it to work, this is what you gotta do:
take a very small hammer, preferably one from a Little Tikes playchest thingy. Take it and beat out the window the sticker is on, make sure ever crumb of glass ends up in your rear seat, or else this wont work. If you do end up with some in your floorboard, don't worry, just get some straws and suck the glass up and place it in the seat. Ok, now that you've got it alll in the seat, get 2 bags of Meow Mix cat food and dumb it on the seat, it soaks up the sticker juice. Now get a vacuum out and get that mess up. Alright, this is were it gets tricky. Go tot he nearest Wal*Mart and get their deluxe oil change and make sure they change your muffler bearing, because if you don't, it'll probably fry your speakers. After you get that done, go back to your "work area". Don't get on it because that could seriosuly screw up some stuff. When you get home, get it up on some jackstands and unhook your exhaust and just let it hang there. Now put in the new window and apply the same brand/% of tint you had on it, preferably from the same box as the other tint. If it didn't have tint, go get some chrome tint and put on it so your car is more aerodynamic. Now CAREFULLY (and i can't stress this enough) put the sticker on the new window. Now hook your exhaust back up. Now get the car off the jackstands. Tunr off all of your assecories (radio, A/C, etc.) and start your car. If you did this correctly, you shou;d hear a bing and see your achievement falsh at the bottom of the screen. Now turn it off, check for sticker juice leaks, and if its all good, fire it back up and enjoy your new horsepower.