Modifications

I pretty much did everything I wanted to with this car. It was great.

Powertrain

FP Red Turbo: The Forced Performance "Red" turbocharger is their middle grade of "stock housing" turbochargers, between the quicker-spooling "Green" and the higher peak power "Black." All three use a stock Evo IX turbo housing with improved compressor and turbine wheels. The advantage of the stock housing is that it has an integral waste gate and essentially bolts right up to your stock exhaust manifold, oil and coolant plumbing. Close, anyway. Nothing like throwing on a big Garrett and redoing your entire turbo system.
GSC S2 Cams: The 4G63 in Evo 8 tuning responds well to cam tuning. The GSC S2 delivers a good 20% power increase without moving the torque curve too much higher in the rev range. Plus they give the engine a race car-like lopey idle you can hear in the video below.
Valve Springs: The GSC S2 cams require improved springs and retainers to deal with the higher valve lift.
Injectors: More air means more fuel. I added Injector Dynamics 1000 cc/hr injectors to make the power and guard against a potential lean condition that would severely damage the motor. Fuel economy suffered a bit.
ECU Tune: A custom ECU tune was required to make all the air and fuel modifications work together.
Turbo-Back Exhaust: I picked up a Buschur Racing turbo-back exhaust with catalyst and muffler on a great sale within a year of buying the car. I still can't believe how cheap this car was to modify. I was a little concerned it was too loud when it first went on, but after a thousand miles of heat and soot it mellowed quite nicely.
Pod Filter: About the same time as the exhaust, I added the Buschur Racing cone filter. I doubt it contributed any power since it was left to breath hot, engine compartment air, but it certainly let the nice, zoomy turbo sounds get out.
Radiator: Eventually the radiator sprung a leak. My friends at Dearing Automotive had a new radiator built for me with custom aluminum end tanks. I wasn't sad to see the OEM plastic junk gone.
Clutch: It was only a matter of time before the additional power overcame the factory clutch. In fact, I'm surprised it survived as long as it did with the abuse I dealt it trying to get a jump into traffic without bogging the engine. Approaching 90 kilomiles a head gasket leak created an oil leak down the back of the block and into the bell housing right onto the clutch disk. I had a four-puck Fidanza and a lightweight flywheel ready to go on in anticipation. The super-grippy material on the four little pucks rendered the pedal more of an on/off switch than the gentle engagement it had before. But it held the power without a hint of slip.

Suspension and Brakes

Tires: Max performance 255/40/17 tires fit the factory 17×8" OZ wheels. I never did purchase the Evo-specific Yokohamas at >$300/tire. My longest running replacements were the Falken RT-615 and, eventually, the RT-615K when it replaced the originals. They performed as well as the 235/45/17 OEMs at less than half the price. But even they were out-classed eventually. I had great luck with Dunlop's new tire at the time, a Michelin Pilot Sport and maybe another brand or two. My last favorite was the Bridgestone RE-11 and, when it was superceded, the RE-71R. Once I tried the Bridgestone Pole Position S-02s which, for some reason, weren't great on this car. Yeah, I've had a lot of tires on this car. It's fun to wear them out and I had this amazing car a long time.
Wheels: I might have liked a lightweight set of 17×9" wheels to better fit the 255 tires painted a low-maintenance brake dust gray, but honestly, there was nothing wrong with the factory OZ wheels.
Brake Pads & Rotors: When the dusty factory pads wore down the rotors at a scant 15K miles, I was done with that junk. I swapped in an aftermarket set of OEM-sized performance rotors all around and added a set of autocross brake pads that squealed like crazy but did an incredible job of dissipating energy time after consecutive time without any significant warm-up time needed. I really didn't mind the noise at all, given the rest of the car. By the time they wore out that brand or model was no longer available, so I ended up going with EBC Yellow Stuff in deference to family members who didn't think working brakes should make so much noise. They didn't have quite the right now impact of the others, but these things are great for a street-driven and even occasionally tracked car. The Evo always had excellent brakes — even better than the admittedly older Porsches.

That's it. The only suspension mods were on wear items. This car was perfect from the factory. With quality, fresh DOT 4 fluid and autocross pads, I expect the brakes would be able to handle anything I could throw at them on a track. Springs and dampers were stiff enough to be highly predictable though not really encouraging of long trips. (That's OK, the exhaust sound was enough to keep me from wanting to drive on the highway for any significant stretch.) A bit tall and way too much wheel gap for the tuner/stance community, but I drive on real roads. Best of all was the incredibly rigid, seam-welded chassis that kept the suspension pick-up points in-place so the moving parts could do their job. This car was so easy to drive fast it blew my mind.

Controls and Instrumentation

Gauges: I added a budget-minded set of essential gauges: boost/vacuum, oil pressure and oil temperature. They went into the DIN slot where the factory radio went. A Mitsubishi relocation kit moved the radio down to the bottom of the stack, replacing a small storage cubby. Eventually a wide-band O2 sensor for tuning pushed the boost gauge front and center to a pod on the steering column. Somehow I never got around to bolting the pod to the column, so the zip-ties stayed on for the life of the car.
Turbo Timer: A turbo timer keeps the engine running for a while after you park. You switch the ignition to "off," pull the key, get out, lock the car and walk away while the engine continues running, flowing coolant and oil through the turbo bearings. After a minute or two the timer shuts off the engine. This particular model also provided a digital boost gauge, lap timer and whatnot it used to help calculate how long to idle.
Solid Shifter Bushings: Solid brass bushings at the lever gave the shifter a firm, precise feel.
Short Shift Kit: Shortened shift linkage on the transmission gave the shifter direct, short throws of the lever.
Shift Knob: A weighted metal shift knob gave the shifter a certain heft. The added momentum made it seem easier and more satisfying to throw the lever fore and aft.
Pedal Adjustment: The accelerator pedal was a bit of a reach from the brake for my size 9s. My low-tech solution was to attach a block of wood to the accelerator to raise it up enough I could blip it with the bottom-right of my shoe with the ball of my foot firmly on the brake.

Exterior

Taillight Film: A little before 2003, the Lexus IS300 (Toyota Altezza mostly outside the US) introduced the styling feature of mirror-finished taillight elements. Immediately this became all the rage among the all-show/no-go crowd, so I simply couldn't have it on my all-go hot rod. A simple solution was to cut red window-tint-like film to apply to your taillight lenses that would make them all red like other cars. A fellow on the Evo forums with a vinyl cutter was making and selling pre-cut films so I took the opportunity (and helped a fellow enthusiast pay for mods). The amber turn signal lights were housed in a separate compartment within the taillight housing and his cut-outs even avoided them. The fit was perfect. Unfortunately, however, the white reverse lights are contained in the same part of the housing as the red brake and marker lights. Thus, when the reverse lights turned on, they shone pink through the red film. I didn't much like that so I ended up trading my taillights with the buddy who bought the yellow Evo in Austin to bring me back to white reverse lights and "Altezza" taillights. Plus the round red lenses inside the housings look kinda nice against the rest of the angular styling.
$\"Altezza taillights\" disguised$

Interior Comfort

Radio Head-Unit: Originally I replaced the factory Lancer head unit in an effort to change the half-red/half-blue interior lighting to all red. It also added MP3 playback from CD-R media. I was surprised how much better the crummy OEM speakers sounded just by adding a mediocre Sony head unit with on-board amps.
Red Dash Lighting: I replaced what other blue Lancer bulbs to match the rest of the Evo red and improve my own night vision.
Dash Camera: I bought a single, stealthy dash cam which managed to catch a number of traffic antics. Next time I want a dual cam setup that records front and rear.
HUD: I got in on the Navdy Kickstarter campaign and scored one on the cheap. It's a pretty slick way to integrate satnav from your phone, voice control, gesture control, etc. onto an augmented reality display the hovers over the road, keeping your eyes on what's ahead. It runs on one of the Freescale i.MX microprocessors I support professionally. Unfortunately my short torso and preferred seating position meant Navdy's tall mounting system placed the HUD too high on the windshield on pretty much every car I tried it on, though the Evo worked out the best. And I was a little disappointed it did not work with OBDII gauges like Torque.