i installed a DIS 4 system last week on my car, it was one of the simplest installs i have ever done. just make sure you get the coil interface adapters.

here is a pic after the install, including covering the wiring with red cond.

as far a HP, it really doesnt make much, just allows you to burn all the fuel that you ingest. it defintly inproved my throttle response, last sat. i had 3 redlights a .418,.458, and a .439 in the second round, which sux. i used TAYLOR wire condu. to cover the harness. i centered the box on the strut tower brace and drilled 2 5/16" holes clean through and bolted it fast. i had no other place to mount it under the hood unless i mounted it to the battery, lol. i ran the power wire to the back of the alt to give it the shortest distance and grounded it to the pcv plate bolt. i got the DIS 4HO box , which they dont recommend to run on the street, its a race app only, so they say. the kit includes a jumper plug that you unplug the harness from the box pigtail and install the jumper in the harness. this will take you back to the OEM ingition system.
also on the strut brace i have this written on it

" ONLY PUNKS DRAG IT TO THE STREET"

i thought it was 5/16" but it was 3/16" holes. i used the top 2 bolt holes and double nutted them. very solid mounting too. i did have to push the map sensor bracket forward a little to clear it. and yes, if you unplug the dis 4 box and install the jumper in the harness, it will take you back to your oem ignition. i have a HO box and they say its race only application so i just use it for the track and short runs here. the standard dis 4 box , you can run all the time. with proper cooling, they say you can run the HO box all the time too. i m thinking about installing a pc case fan so it blows cool air on the dis 4 box too to help keep it cool.