Upgrade: ST 1 to Hybrid K04 1.8T


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Upgrade: Stage 1 to Hybrid K04

Please select this option if you are upgrading to either an OEM BorgWarner K04 or a Hybrid K04 turbo.

*Please contact us with questions about model years

Required Upgrades:
Current Motoza Stage 1 Tune
Injectors (Bosch 550cc or larger)
Upgraded Diverter Valve
K04 or Hybrid K04 Turbo
Recommended Upgrades:
High-Flow CAT
3″ MAF Housing
Power Gains:
260-300+hp / 300-375lb-ft


*Power gains are subject to vehicle’s condition and fuel type.
For customers planning to run E85 with a hybrid K04, we suggest at least a 750cc injector and upgraded rods.
Please feel free to contact support regarding the ideal injector for your build.

Tune upgrade is a virtual product and will up uploaded to your user account. Box images are representational only.


  • Flashed DIRECTLY to the ECU with remote tuning kit (included FREE)
  • Flash your tune in your own garage, no need for a dealer
  • Extensively tested and proven to provide superior performance
  • Stock Block includes 3 log reviews, Built Bottom End 4 log reviews, Heavily Modified Block includes 5 log reviews.
  • Increased power and torque
  • Optimized for responsiveness, drivability and smooth operation
  • Rev-limiter raised
  • Speed restrictions removed
  • Easily upgrade your tune at a later time
  • Upgrade to MTC (multi-tune control) available

Modification Options

A K04 or hybrid K03/K04 is a fantastic choice for many drivers. Enough power to keep things fun, quick spool to get you out of corners, and they can be installed with minor modifications. They suit many driving styles and budgets.

They can also be installed with serious modifications. and everywhere in between. This chart is designed to help you sort out where you want to be or where you are. Upgrades between these stages may be purchased as your build develops.

The K04 is often an interim step before going to a larger turbo like the GT30 series so there are cases where the supporting mods are well beyond what’s needed. Supported does not indicate recommended but is intended to give you flexibility if you prefer to take things a step at a time due to budget, time, etc. We’ve taken K04s to their limits, but that’s not necessarily a practical option for most people; it involves a lot of upkeep and may shorten turbo life. If this keeps you in your current racing class, and you are aware of the limitations, we’re all for it. Sometimes the quick spool of a K04 is just what you need for what you do. There is also a point at which physics intervenes and all the supporting mods in the world won’t make a K04 act like a larger turbo.

Where noted, some items are supported only on the “Heavily Modified” option.

MAF/MAF Housing Project Type Notes
Stock MAF Sufficient for stock block projects
Stock MAF sensor with TT225/VR6 housing or 2.75″ ID aftermarket options -OR- TT225/VR6 complete MAF Covers the vast majority of K04 projects on 1.8T, stock or built block. 3″ outer diameter 2.75″ inner dia. May include aftermarket housings with the same dimensions. If using a complete MAF rather than the stock sensor and housing, the MAF part number will be required.
Stock sensor in B5  or B6 S4 housing Far more than most K04 projects will ever need. Only supported on heavily modified builds.
Blow-through MAF Well beyond what any K04 project needs. Only supported on heavily modified builds, not supported on MY 2000/narrowband vehicles.

Fuel Pump

Aftermarket fuel pumps are supported at any level. Stock block projects on pump gas may use the OEM pump if it’s in good condition, if it’s falling short, an upgrade may be needed. We strongly suggest upgrading for E85 use with the stock block. Most modified block projects and all heavily modified builds will need an aftermarket pump.


Unlike many modifications, intercoolers and fuel pumps are in the bigger is better category. Larger intercoolers are supported on all levels and strongly recommended in hot climates. Stock block builds in mild climates can usually get away with the stock intercooler or an upgraded side mount.

Diverter Valves

Piston style valve with spring options is ideal. Fully recirculating or hybrid valves may be used. Hybrid valves must be set to full recirculation during tuning.

MAP Sensor

The stock MAP is ideal for most projects and for turbo longevity. 3bar MAP sensors are only supported on the heavily modified option. Requires rods. In most cases we do not suggest going 3bar with a K04.  As a general rule going to the edge of what a 3bar sensor can meter is not advised and is counter productive with a K04. We will only raise boost to the 3bar limit under very limited circumstances.


Not all needed. Supported as part of an upgrade path to a larger turbo, or if downsizing the turbo on a previously built engine. Definitely part of the heavily modified tier. Aggressive/race cams are not included at this price point but can be supported for an additional charge. “Street” cams and cams from other Audi/VW platforms are supported.

Throttle Body

It takes a lot of power for the stock throttle body to be a restriction. More than you will ever produce with a K04. Also in the heavily modified tier. Throttle bodies produced by Audi/VW may be included at this price point. Aftermarket throttle bodies are not included but can be supported for an additional charge.


Any exhaust may be used, but additional track car verification may be required for full support.


Injectors are the heart of your build. They need to be genuine Bosch or properly modified with a detailed flow report. Injectors must come from a reputable source, there are too many counterfeit and subpar rebuilds that do not flow as advertised, may damage your engine, and they waste time and money and we will not support them. This site is, of course, a reputable source, but there are others and we will gladly share that list via email. It even includes other tuning companies; we’d rather you buy genuine injectors from another tuner than purchase cheap, ineffective, or knock-off injectors. Injectors purchased on auction and third party sites that ship in boxes with smiles on them are not worth your money & time. In short, if you are looking for places to save money on your project, injectors are not the place to do it. 

Left: Genuine Bosch 0 280 158 117. Right: “Remanufactured” 550cc.

Modified Injectors
750cc and larger should be flow matched.  They should come with a flow report for the exact set of injectors you purchased, not a generic one.  Static variance on quality injectors is typically ~2% and under. Variance should be less than 5% for use on the stock ECU and should be noted on your flow report. Spray pattern matters, especially for E85 use. It’s simple enough to increase the flow of an injector, it’s not as simple to to increase flow and retain spray pattern.

The Correct Injector
Bosch sells injectors for numerous applications Injector size alone is not indicative of a proper injectors. EV-14 refers only to the body style. For an OEM 550cc, there should be 6 openings on the nozzle and the part number is 0 280 158 117. The injector on the left is Bosch, the one on the right was purchased from a place that rhymes with relay. Not only is the filter basket on the right incorrect, but in this case the housing spins right around the body. When tested, the injector on the right flowed around 200ccs at 3bar pressure. That’s less flow than stock. Not all sub-par injectors are this easy to spot, but the stories about cheap, failed injectors are very easy to find online.

There are injectors that were popular in the past that may be appropriate for pump gas applications, but are not appropriate for ethanol use. Some of these are not ideal in terms of spray pattern or how they respond to tuning. We can work with them, but for the best results please follow injector recommendations. We will support Bosch 621/630cc injectors. We will also support Siemens, but there is an additional $50 fee and they may only be used with pump gas.

If you don’t want to purchase multiple sets of injectors for multiple stages, we get it. It’s better to have and not need when it comes to fuel availability, but not at the expense of quality and reliability. Feel free to reach out with information regarding the injectors you have or want to purchase. If injectors are not responding the way we expect for their size once tuning begins, a comprehensive flow test may be required from a select list of testers at your expense. Should they fail flow testing, new injectors will need to be procured before tuning is resumed.
Please note: all software and hardware sold on this site is sold for off road use only. Use of this site and purchase of products from Motoza Performance, INC and motozaperformance.com constitute acceptance of all terms of service.