Audi A4 1.8T Tuning Guide


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So you got a B5 A4 I.E. 1996-2001.5(1996-1999 = pre facelift, 1999.5-2001.5 = facelift), NICE! However, everyone else has an A4 and lots of them are faster and nicer then yours so before you ask dumb questions, use the search button a lot. also read everything on here. I REPEAT, SEARCH! AND READ EVERYTHING HERE BEFORE POSTING A QUESTION.
Lets start out with factory options. Sport suspension has red shocks. To see them, look behind your wheels with a flashlight. If you have the cold weather package, good for you. Now onto the important stuff. Tiptronic basically sucks, its not “both”. You have a clutch or you don’t, I hate when people try to say they have both. If you have stick, awesome. 5 speed is the superior! As for motors, if you have the 2.8 (30v or 12v) some people like it. Basically all you have is an intake, exhaust, short shifter, and chip(30v only). The chip is not going to do as much as a 1.8T chip but still helps. 30v's also have the PES supercharger ( If you have the money go 4 it! PES states that you can bolt the supercharger to the 12v but you need s/w. I.E. standalone
Im going to focus on the 1.8T here because most of us have that. Here are pretty much all your mods that you can do…a lot are universal so can be used for the 2.8 too
1. Intake – Ok so many cars can gain power from intakes but we cant… The only one that people like is the Carbonio but is it worth the $300? It has been proven to show increases and some think it is but its all preference. there is also the Evoms one but the stock heatshield that comes with it sucks. if you want to hear your turbo spool and your DV or recirculated BOV go psssht! then get a cone type filter(Evoms or homeade) and get the "true heatshield" LINK. all in all the stock airbox is good for about 300hp
2. Exhaust – Because our cars are turbo, freeing up room for the turbo helps bring out power, so an exhaust is important. There are many companies (Borla, Milltek, APR, and Neuspeed are the most popular off the shelf ones). Some like it louder, and some like it softer. Borla would be the loudest then neuspeed. miltek and APR are stealth type exhausts so they are very quiet.. Make sure you get a good diameter depending on how much power your going to be putting out.
2.25"-ko3 power
2.5" to 2.75"-ko4
2.75" and up- BT
3. Test Pipe/High Flow Cat – As I mentioned before, freeing up room for the turbo is essential. A test pipe (TP) replaces the catalytic converter (cat) and makes for a quicker spool, more power, MORE NOISE! and a CEL(check engine light). to get rid of the CEL you have to do the "anti-fouler mod"~search it in the forums. Its an awesome mod but many stay away because it may be illegal in your state and the fines could be huge. it can also smell. Check if your state runs emissions tests on inspection.. a better way is to get a highflowcat (HFC) Miltek makes one that is good but $$$.. best one to get is the Labree one.. only slightly more than a TP and will be legal in a lot more states. and the HP differences between the two wont be noticable.
4. Chip – A chip is probably the best bang for your buck and the most favored by most 1.8T owners. It remaps the feul and boost to push more hp on your car. The main companies are GIAC and APR. there is also Dahlback and neuspeed . Many choose based on which dealer is closest~very important. GIAC is the only one with upgrades for K04.. Dahlback also does but you need their expensive KO4 too..
5. Turbo Intake Pipe (TIP) – The OEM turbo intake pipe or hose can be faulty and collapse under added pressure. A new TIP is a popular mod to make sure the collapsing never happens. APR is the most stout but is only available for the K03 and K04. The Neuspeed is 2nd on the list. It is less stout but still very good and can work for the K03/K04 and the eliminator applications.
6.Boost Gauge – A boost gauge monitors boost from the turbo and is VERY recommended to make sure everything is running smoothly. AWE makes a nice one, as well as ECS Tuning's pod and VDO guage combo.. VDO is a cheap and good guage and the lights match our interiors very nice
7. MBC/EBC – A manual boost controller or electronic boost controller is used to limit the boost that is put out by the turbo… EBCs are better but cost more and there are some MBCs that are better than others -DO NOT HOOK UP ON OF THESE THINKING THAT YOU WILL CREATE MORE POWER- our ecu's do not work that way
8. N75Valve – This controls the smoothness of the boost essentially. Many people throw in an N75J or N75H valve to increase performance (which it does) but it makes the boost come in very harshly and can possibly put your car into limp mode (when your ECU restricts boost because it knows something is wrong)
9. Diverter Valve/bypass valves in general – A diverter valve is most popular and is required for all chip and turbo applications that run more boost. It holds the extra pressure better. Forge 007, Bailey, Hyperboost, and other DVs are good. an OEM 710N DV will hold chipped boost without a problem and is a cheaper soulution. The blow off valve (BOV) is asked about. some say don't do it and will flame you. but as long as you take the necessary steps it can work. you just need to run a recirculation kit to make it work, basically taking the "blown off" air and runnning it back into the intake tract like the DV does initiallly.
10. Short Shifter – Some consider this an Interior mod some consider it an engine mod. Basically it shortens shifts so there is less time in between. Neuspeed and B&M are popular. DieselGeek is also an awesome one for less money too. Ebay is also a great cheap one that people have had good luck with.
11. Snub Mount/D.T.S. – this is the front engine mount of our motors. the stock one is a squishy rubber that allows a lot of play in the drivelines. upgrading to a polyurethane unit cuts out a lot of the slack and rubberish feeling while driving. The APR, Greedspeed, Vastperformance, and 034 snub mounts gets rid of the shifter/drivetrain clunking when hard shifting occurs. Its cheap and an easy DIY for us, go for it! the DTS, or drive train stabalizer, is a unit that bolts directly to the undercarage of the B5 using existing hardware and mounts. it also bolts up to the transmission reducing yet even more driveline slack. it's an easy install. a word to the wise though, throw away the junk rubber mount that comes with it and get a polyurethane one More info here. the two places that sell them are AWE and ASP. both are the same only a slight difference in price. but ASP is the only one that has a DTS for a TIP transmission.
12. Clutch/Flywheel – a great man once said "Stock clutch wasn't rated for stock power" [URL=""] [/URL]. When going past a simple chipped setup, with the added hard driving a clutch may be needed. It allows for better launches and better grab between shifts. ECS tuning sells a decent clutch but Southbend clutches are the best. The OFE SS is the top dog while the HD is a step lower. Make sure you get a new OEM dual mass flywheel when you get the clutch. Everything should be around $1100 without install.. our cars have a heavy DualMass Flywheel, DMFW, that assists in balancing and honing the engine. it's dualmass is separated by rubber bushings so this is yet another source of the rubberish feel to our cars. there is no problem with the DMFW other than its ~24lbs. a lot of people keep it after a clutch upgrade for numerous reasons. depending on the shape of it you can easily resurface it with a heavyduty scotchbrite pad.. as for a Light Weight Flywheel, LWFW, there are many options, Unorthodox, Fidanza, AWE-tuning to name a few. they will help your car rev quicker but some say it's too much for a daily driver. hard to shift smooth and creates chatter at idle due to our internally balance enigines.
13. Intercooler – An intercooler is an effective and sometimes essential (for K04 or bigger) way to cool down IATs (Intake air temps) from the turbo so more power can be made. The FMIC (front mount intercooler) is the most effective and is placed in the front bumper. Evolution Racewerks is the best-once released that is. Racetek and APR are also nice pieces.
14. Exhaust Manifold – A turbo manifold will open up your exhaust ports, allowing for more flow for the turbo. ATP makes a crappy one that most people use. APR has an awesome one on their Stage 3 kits, and there are some other ones that I cant think of. It is not required with the Eliminator kits but recommended. Most just bite their lip and get the ATP. for BT setups most go ATP as it is the only one easily available for cheap.
15. Intake Manifold – Our stock ones are sweet, don’t worry about it, the Dahlback one is garbage.
16. Turbo – So now you have your FMIC, clutch, exhaust and your ready for the new turbo and software to go with it. NICE!
Turbo Options
This is meant to be a short guide to turbo upgrades. There is a ton of info around here and other forums. Please make sure you use the search for additional info on the type of upgrade you're looking at prior to making a hasty decision.
Some highly recommended parts to get before upgrading your turbo are pretty much all the things that you have just read in this. so get those first as there are certain steps and and order to things.
The ko4 that you want is the ko4-15. Basic bolt in upgrade. No special required parts unless going for the pc-16, J31, or Hammer files from GIAC. Do not pay more than $800 for a K04 alone. They can be found on any of the various Audi forums for less. GIAC makes a very good program for it. $1300 and an install later you can be rolling with 200whp. When looking you will need the K04-15. do not bother on doing a ko4 for your 2001 A4 if you are not going with the Hammer file. the 2001 model year has the ko3s(sport) so there for the GIAC-X chip with the ko3s will only be slightly less powered than the ko4 on basic GIAC programming. for knowing what you need for these setups contact GIAC directly. as it will be easier than me typing it all out. KineticMotorsport has them for a good price usually
PC-16 - 1997-1999.5 model years~usually runs in the 20-25psi range
j31 - 2000~usually runs in the 25-28psi range
Hammer - 2001 and 2001.5~i think usually runs in the 20psi range
GT2X Eliminator
Bolt in upgrade. Slightly larger than the K04. Good for 220Awhp. Most people use the Mika tuning from ATP, others use modified K04 software. it is only oil cooled unlike the other eliminators
GTRS Eliminator
Bolt in upgrade. Much larger than the stock K03. Produces roughly 350chp. Mika tuning or Unitronic for the B5.
GT2871R Eliminator
Bolt in upgrade. $95 more than the GT28RS elim. good for 400chp. Mika or Unitronic for the B5.
Note: For the eliminators, I highly recommend a braided oil return line. The stock oil return will work, but it's a pain to get in. Unitronics for software, but also Mika tuning offered by ATP can be a good software. but FWIW not off the shelf. it requires tweaks to get things running right. some have run tweaked ko4 software with success on this big of a turbo. ATP and Renn-Art are the best places to get the eliminator products. Renn-Art has a proven kit.
APR Stage 3/Stage 3+ kits
APR has a stage three kit with everything you need to get your BT up and running. they have their stg3 GT28r kit for 1997-2000. and their stg3+ GT28RS kit for 2001s. both are very respectable and worry free kits that a lot of people love. APR's website for more info

Full GT28RS
Requires ATP or custom exhaust manifold, custom downpipe, and custom intake. Approx 400chp, depending on the tunng and supporting parts. Needs custom tune, standalone, or dyno tune.
Full GT2871R
Requires ATP or custom exhaust manifold, custom downpipe, and custom intake. Approx 400-450chp, depending on the tunng and supporting parts. Needs custom tune, standalone, or dyno tune.
Requires ATP or aftermarket exhaust manifold depending on flange, custom downpipe, and custom intake. hp numbers vary as there are numerous different sizes, Trims, A/R's and such. Requires custom tune, standalone, or dyno tune. CTapp is also a good option for software.
GT2871R elim vs GT2X elim vs Stock K03
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17. Water/Meth Injection - Ok so the new big thing on here is water/meth injection. Basically it allows for a water/meth mixture to be shot into the intake manifold to lower temps and allow for more timing (such as running a race file on pump gas). The DevilsOwn and SnowPerformance kits are great. It is AWESOME but the effects could be dangerous if correction factors get too high. Check out Timing 101 near the bottom if you have no idea what Im saying
18. VAG-COM - This could be one of the most important things you get for your B5 as you start to mod. VAG-COM is a software made by Ross-Tech ( that can Erase/Read CELs, Get rid of the seat belt chime, enable remote windows up/down, and most importantly, LOG! With VagCom you can log IATs, knock, CFs, RPMs, Engine Temp, blah blah... Here is the website to see more features B5 VAG-COM... Its about $220 from them for the full licensed verison or you can get an Ebay cable and get the lesser version for $20-100 for that cable
19. Suspension - Suspension is just as important as power. Being able to control your car is essential and coilovers or shock/spring combos allow for this... There is much controversy over which ones are the best. Stasis products are great. Their tracksports and motorsports are well known. The Bilstein PSS9s are also highly recommended. H&R is good quality. Vogtland and KW make fine products also. for the more frugal individuals the Eibach Pro-Kit coils, Koni Coils, and Stasis Streetsports get the job done! As for shocks and springs, Bilstein/H&R is most popular. also Koni shocks and eibach and neuspeed springs work well too. just put them together in the right combo.
20. Sway Bars - Neuspeed (29mm front, 19mm rear) are good. H-Sport's(35mm front, 22mm rear) are by far the best. either ones that you get, make sure you get the reinforcement bracket system. some that have run without them have cracked their subframe's.
21. Brakes - The simplest upgrade is an A8 312x25 rotor with Porsche caliper brackets(with special brackets from ecstuning or If you do it right, you might not even need to bleed them. in the future. This fits with almost all wheels, even 16's. ECS tuning has some awesome Brake systems that you need to check out. also stainless steel lines are a cheap way to improve the braking feel. they don't expand like the OEM lines thus making the braking more firm and responsive.
21. ECU/Engine Codes - our car's generation is broken up into two different ECU's and three different Engines for the 1.8T.
1.8T AEB = 1997-1999
1.8T ATW = 2000
1.8T AWM = 2001
AEB is DBC(drive by cable) or a.k.a. nDBW(non drive by wire) meaning that there is an actual cable conected to the throttlebody. which is more easily tuned
ATW and AWM is DBW(drive by wire) means that the ECU, the computer, controls the throttlebody. harder to custom tune and can have a mind of its own sometimes..
AEB has the larger port head and 20 mm wrist pins.
"ATW is the ******* engine w/ the AEB bottom end and the small port AWM head" 94jedi.
The AWM has 19mm wrist pins, small port head and internal waterpump
22. TimingBelt - our engines are interference engines meaning that if the timing belt breaks, waterpump fails, or tensioners fail then the pistons slam into the valves bending them. and costing you big money to fix. audi suggest that the timing belt and such be replaced in 120k intervals. but experience has shown that that is false. they should be replaced in 60-70k intervals to be safe. some have gone longer but it's not worth the risk. the change is a strait forward process it just takes time due to the entire front end has to be removed. ECS Tuning and Purems sells the best kits for a worry free switch.. it's best to do all belts, rollers, tensioners, and waterppump at once since you already have the front end off. and this is also the best time to do a Snub mount that i mentioned earlier. takes 2 minutes to install during the TB process.
23. Headlights - there are two different sets of headlights for our cars. pre facelift's have two peice non projectors where as facelift's have one peice projector lights. 2000 and 2001 had HID's as a factory option. 4300k and you will know if you have them by looking at them while on. if not there is a ballast on the back of the headlight housing that has a lightningbolt on it. if you don't have HID's then no worries because they are a cheap and easy upgrade. provided you have projector housings. if you have 2 peicers then first upgrade to OEM projectors, Valeo Ecodes(the best), or even Depo Ecodes off of Ebay(but stay away from all other Ebay lights!). is a popular place to get a good kit, link down below. also Ebay has some good kits provided you buy from a reputable seller.. OEM 4300k are supposed to have the most light output you can get. then there is the 6000-6500k which is the most pure white you can go. 8000-10000k are bluish and beyond that is purpleish. 3000k is a yellow and a poplular choice for foglights. All bulb numbers can be found here

Performance Parts and Tuning:
Brembo Brakes
Dahlback Racing
ECS Tuning
Stoptech Brakes
OEM Parts:
1.8T Troubleshooting Guide-LOOK HERE IF YOUR CAR IS ACING UP.
B5 A4 External Differences
VAG Tool Locator - Registry of individuals with Audi/VW VAG tools.
Bentley Fault codes
Decoding VAG fault codes
logging blocks with VAG-COM - great HID kits!
Can all be found here