You're basic bolt ons are pretty standard compared to most other turbo applications.
- Intake
- Down Pipe (3")
- Test Pipe (3")
- Cat-Back (3", 80mm is popular too)
- Boost Controller
- Upgraded DV
- Fuel Pump
- Intercooler
.... and finally a good custom dyno or road tune. (more specific than a generic "flash" or "chip").
There is plenty more that can be done, but those are enough to get most people started and still cheap enough while showing a huge improvement over stock.
Comparatively though, the same mods on an STI wouldn't ever result in as much of an increase in power output. While nice, the STI's just don't take to mods as well as Evo's, and parts for the STI are far more expensive as well.
The mod list from my Evo consisted of pretty much every possible bolt-on for the stock turbo, minus 2 pieces I never got around to doing; a tubular manifold and ported O2 housing (upper exhaust piece prior to down pipe).
Engine/Drivetrain:
- Custom Road Tune (93 octane specific)
- 272Intake/264Exhaust Cams (stock lift)
- Forge Motorsport Unos Manual Boost Controller (Black) - 22 PSI
- Forge Motorsport EVO15 Recirc. Diverter Valve (Polished)
- Forge Motorsport Piston-based Wastegate Actuator - 19-24 PSI Spring (Polished)
- Forge Motorsport Evo 7/8/9 Alloy Radiator w/ Ralliart 1.3 BAR Radiator Cap
- Forge Motorsport "prototype" one-off Custom Intercooler
- Forge Motorsport Radiator Hoses
- Forge Motorsport Intercooler Hoses
- Forge Motorsport Alloy Coolant Tank
- Forge Motorsport Alloy Power Steering Tank
- AMS Lower Intercooler Pipe
- Walbro 255 lph High Pressure Fuel Pump
- Samco Sport Silicone Turbo Intake Hose
- Blitz SUS Power Intake Kit
- NGK BPR7ES Spark Plugs
- Invidia Down Pipe - Custom Heat Wrapped
- Invidia Test Pipe - Custom Heat Wrapped
- Espelir JGT-500 Cat-Back Exhaust (80mm)
- Buschur Racing Short Shifter
- Buschur Racing Under Hood Shifter Bushings
- Brass Shifter Base Bushings
- Powerflex Complete Motor Mount Bushing Set
- Removed Clutch Restrictor
- Magnetic Oil Drain Plug
- Revised Vacuum System
Not to brag, but that was just the engine. :wink:
http://www.golfmkv.com/forums/showthread.php?t=11418
I don't have any dynos handy, but other Evo's with comparable mods and tuning were approaching 380whp and 380+ wtq.
Evo 9's with the slightly different turbo and MIVEC intake cam are a little more capable (just over 400whp/wtq) with the same modifications.
Beyond that level, you're basically looking at upgrading from the stock 16G turbo.
Both the Evo 8 and Evo 9 use "16G" turbos, and though there were slight differences between them, like a slightly larger compressor cover and a lighter wheel assembly (center cartridge) on the 9 turbo, they were otherwise the same, and the other main factor to the increased power output capacity of the Evo 9 was the MIVEC on the intake cam (variable cam phasing, NOT lift).
'03 and '04 Evo 8's had a 9.8 cubic cm exhaust housing whereas the '05 Evo 8's had a larger 10.5 cubic cm exhaust housing which offered more exhaust flow. The rest of the turbo otherwise was the same, so a common upgrade on '03's and '04's was to a 10.5 hotside from an '05.
Once the Evo 9 was released, the popular upgrade became using a 9 turbo on an 8, which offered some better spool characteristics, higher peak boost, and a larger overall boost curve, with proper tuning of course. You'd never quite get as much as a 9 with the MIVEC intake cam, but the turbo alone got you about half of the difference.
Beyond that, using OEM components, you get into 20G turbos and changing between 5 and 6 blade wheels, but those types of things are far less common than some forums would lead you to believe.
After that, you're looking at Garrett GT series turbo upgrades, the most popular being the 35R.
On either an 8 or a 9, using any turbo other than that which was stock will require larger injectors, but the stock injectors (though different between an 8 and a 9) are usually suitable for virtually any stock turbo application.
