Fuel Injection:

Use a K&N Air Filter and cut a good size rectangular hole in the top of the air box this will improve the flow through the filter by approximately 50%.

Install a Weltmeister throttle cam this greatly improves throttle response by modifying the throttle profile.

Remove the cover on the airflow-metering valve (Bosch L Jetronic) and weaken the spring tension one notch on the flapper valve. Reinstall the cover. This will eliminate the off idle hesitation and quicken acceleration off idle. This will also slightly increase the fuel schedule (consumption) and emissions across the operating range.

Adjust the Motronic DME brain box (under the dash) by accessing the eight position rotary switch through the little hole on the back of the box. Use a carved out golf tee to turn the switch and set the switch to position number four. The factory stock setting is position one on North American market cars. This will lean out the fuel mixture by three percent, decreasing the injection pulse width. These tweaks will dial-in approximately 5 HP.

Exhaust System:

Replace the catalytic converter with a flanged test pipe (interchanges easily and quickly with the original converter) or use a glass pack straight through muffler (such as a cherry bomb) this will decrease back pressure, increase mass flow and increase horse power by approximately 10 HP.

Don't worry your Bosch Fuel Injection system was designed accordingly and is self compensating. Although, if you have adjusted your DME box to a leaner setting you might want to return to the stock position for a richer fuel setting. Or you might try an even richer setting such as position two, which is three percent richer. Some testing will help find the best setting for your car and the modifications you have made. Always check the color of your plugs before and after test runs.