i had to cut the speedo cable to fit, and cut a piece of the carpeted firewall crap off, had to buy a new belt because sice my A/C isn't hooked up, it took about 5 trips to autozone to get one that fit, which was a pain in the ass to get on too..had to make new tubes for fuel and crap that was about it, oh, um and remake my intake tube so it would fit , since the sc' comes off sideways. i bought the s/c out of a pure decision. Nitrous, had it, want it again? no. Turbo too much $$$$ and too many things can go wrong. Supercharger? cost me $1500 dollars. and about 0 to install, since my dads shop can make almost anything (i might have a pulley made for more boost) and i bought a used jackson racing boost gauge, topping at 5 psi, its fun, but it's not where i wnat to be, probably the biggest problem is fuel/air. the tb is way too small, 55mm, i bought a focus central 65mm tb to fix this, and am going to get a new fuel rail and injectors to correct the leaning problem which i believe it has. i have a chip, but dumb me never took it out, which is maybe why i only ran a 15.8 , took hectors advice and took it out, car seems to run a little different, but still need to get that new atx sensor.
all in all, i thought it was a good decision given the room, the limits of my engine, and $$ at the time, that and since i can make like anything for nothing.
btw, anyone wanna buy some rolls of carbon fiber