Originally Posted by FAQ

Basic Mods


CHIP
Increses both boost and timing to give a substantial gain (see tuners' website for claim).
Popular tuners - GIAC, APR, Unitronics, REVO, and Nuespeed.
- please aviod upsolute, eip, and any budget chips.

DIODE
For those w/o the money for a chip or plan to upgrade turbos sooner than later, a diode is a simple upgrade to increase boost. The diode limits the voltage from the map to the ecu and prevents the ecu from going into limp mode (5psi) for passing 1bar. The o2 and maf will make up the fuel for the increased air. How to and more explaination here.

DV/BOV
After the increase in power, it is a good idea to also upgrade the stock dv. The 225's 710n is a rather durable dv and should withstand a good deal of power. Only problem is that like all diaphrams, it can wear out or tear. A piston valve doesnt work as fast but is tunable and far more durable. There are good diaphrams available such as those from apr and hyperboost.
good valves: forge007, apr R1, hyperboost, turboxs h25, greddy, hks.

Bovs are ok to use on the car, but not all cars will accept them with stock power. To use them, you MUST have a valve that is closed at idle. These include a twin piston valve and a HKS ssqv. This prevents thecar from stalling and leaking air at idle. It will also not run rich after the car adapts (sometimes not needed to at most 2 days). The best bovs are the forge004 and ssqv. For BT applications, a tial 50mm bov.

DOWNPIPE
A downpipe is probably the next biggest gain after a chip. It frees up the exhaust flow and makes great power.
- 225- 42dd dp or apr with full turboback.
- 180q - tCarbon and 42dd either do or will have dps available (no, a 225 dp doesnt fit)
- 180fwd - any VW 1.8t will fit. Ebay dps are cheap and fit well.

CATBACK
Great way to finish off the exhaust. A 2.5" is the min and 3" max for all 1.8t's.
A 225 catback will fit on a 180q car.
there is no good way to make a fwd have dual exhaust, but miltek has a kit availble

INTERCOOLERS
FMIC's will cool the increase in heat from the turbo when the car is chipped. In the summer time the car could use an upgrade.

TIP
a turbo inlet pipe willsmooth the airflow to the turbo. The 225 sometimes has a problem with it collapsing since it is all hose. The upgraded hose will prevent that. The 180 will have a smoother path since the cast peice has a smaller 90* bend.

INTAKE
Not a real gain here. You will see a change in throttle response, but no real hp gain. Just remember that on a turbo car, flow matters and temp not much. Get the best flowing intake as possible.

SUSPENSION
springs/shocks or coilovers. Both are a great upgrades. The main differnce is the coilovers can adjust ride height where springs cant. Always replace the shocks with performance koni/bilstein since the stocks will die fast and the newer shocks will give a better ride.

SWAYBARS
Another great and often overlooked part. By adding/increasing the diam or the rear sway bar, you will gain a more nuetral car if not gain some oversteer. Just take into account that if you plan on doing both front and rear, they need to work together. Its best to stick with the same brand since they are made to work together.

BRAKES
With amildy modded car (chip and bolt ons) just a simple upgrade in pads will help greatly. With more power it is recommended that you increase the brakes further with a BBK.
brake basics:
- solid rotors - simply a solid metal rotor
- vented rotors - have vanes between the front and back of the rotor to vent heat out of the rotor
- plain - have a smooth face
- slotted - have channels cut in the rotor. Cleans the pads and lets gas escape.
- cross drilled - have holes in the face to push water and gas off the pad/rotor.
- 2 peice - have a aluminum hats on a zinc rotor. Cools faster and removes a good deal of weight

however the xdrilled and slotted rotors look nice, they actually remove surface for the pads to make contact with the rotors. Its best to have a plain face for just a mild street car. Also avoid buying xdrilled rotors from a non name source. Even if they use name brand rotors, doenst mean those are the people that drilled the holes. These are known to crack easy when the heat is to much.

HALDEX CONTROLLERS
Those with quattro can get a controller that improves how fast the power is sent to the rear and how much. Not really going to see a huge unpgrade on the street except on launches. Best if used on cars that are tracked. You have 2 choices, a blue and orange. The blue is more mild and recommended for street cars since it disengages the rears when braking and the orange does not.

WATER/METH INJECTION
A little more advanced but can make a significant improvement on the stock turbo. It basically lowers the iat (water) and increases the octane level (meth). This allows you to increase boost/timing to gain power. To take full advantage of this you will need both a vag com cable (ross-tech.com) and unisettings (from unitronic). Other benifits are it reduces knock and cleans the cylinders. For more info, use the search feature.

WHEELS/TIRES
a commonly over looked part. Lighter wheels and stickier tireswill make the car go faster due to less unsprung weight. Also the tires will stop the car much faster.

WEIGHT REDUCTION
a simple and ofter free mod. Less weight = less to get moving. This can increase 1/4 times (100lbs lost = .1 sec) and mpg. Just dont remove anything safty related than can cause harm when removed: ie crash bar. Cleaning out the engine bay


COMPLETE IDIOTS GUIDE TO MODDING A 1.8T

STOCK TURBO TUNING GUIDE