ECU Upgrade


The following is a discussion of the modification I did to the cars ECU chip.


More Power.


Choosing a tuner that I felt comfortable with. I thought about their reputation of product design, customer service, price and performance. APR has had a great reputation and one visit to their web site demonstrates that they are a company that is working on new and innovative ideas. Their price was comparable to other tuners and the results of performance tests led me to conclude that there is a negligible measurable difference in the performance of the top tier tuner’s chips.

Audi B5 S4 Engine Computer

Options Available:

  • GIAC
  • MTM
  • TAP
  • APR



APR logo


Adding a chip to the modifications I have done to my car was one of the best improvements I have experienced. Only the addition of my Coilover suspension produced such tangible improvements in performance.

Audi B5 S4 at APR facility
My Audi S4 at the APR facility in Alabama

Installing the chip is a very easy process and takes about 10 minutes when you know what you are doing. Adding 50-60hp is a real noticeable change.

Others will argue that you should attend a driving school to improve your skills at handling the car prior to adding so much horsepower. I had attended such a school a couple of year’s prior, but I do not support this position. I did not purchase the chip so that I could drive the car at higher speeds or in a more aggressive manner.

I wanted the extra power for those times when accelerating in a hurry was very important. Passing on a two-lane road is one place when the extra power comes in very handy.

I have been very pleased with the performance of the APR chip and the support they have shown for their product.

Long-term report:

In all I used the APR chip for 4 years. I never had any problems with it; my turbos and TBB never failed, though I replaced my DV’s as a precautionary measure. It was reliable and provided a substantial boost in power. I was glad to see APR revised the code when it was determined that it was suffering from poor timing in the mid-rpm band. It was very smooth in terms of drivability.

Historical Document:

This link is to a PDF file of an article in the European Car magazine about APR, published in 2000 when tuning of the Audi’s was just in its infancy.

Audi B5 S4 Information and Testing