I have been tuning turbocharged cars for many many years and have tried all types of mechanical and electronic boost control devices. I decided to have a go at making my own so did a bit of R&D. I chose a relief valve mechanical boost controller after doing a fair bit of research and speaking to a number of people directly and via the internet. Many of the net resources I originally used are gone now but I will try and restore some ASAP.

The costs are significantly less than an electronic boost controller and the results are superior to the conventional bleed valve which most people know about and use.

To this end I decided not only to use one myself but also to supply them to people who wanted one. Since the valves are not readily available to motor enthusiasts, mainly because they are not yet recognised as a main-stream alternative to a bleed valve, I have to source the parts from the United States and manufacture them.

The following pages comprise of instructions and tips supplied with each boost controller ...

Introduction to relief valves
Information specific to the Celica GT4
Installation instructions
Setting up

In addition if you wish to increase the boost levels beyond the factory limit, check out my fuel cut defender section where you can buy one to complement the relief valve or any other form of boost controller.