Turbo Diesel and Petrol cars, bakkies and 4 x 4’s now have the benefit of increased power and torque with a properly dyno-designed exhaust system consisting of:
1) Down pipe:
The down pipe is the most important exhaust section relative to proper exhaust tuning; the trick being the different formats employed to increase flow and reduce back pressure right at the turbo exhaust flange. We do dozens of turbo vehicles and invariably we come across turbo cars, 4 x 2 and 4 x 4 (diesel and petrol) with so called free-flow systems fitted by your friendly fitment centre around the corner, which are totally incorrect in terms of pipe diameter and down pipe design.
2) Exhaust system after the down-pipe:
The silencer system diameter must complement the design and format of the down pipe and here the box application will determine not only the sound or loudness of the exhaust tone but also affect the intensity of the resulting “drone” inside the vehicle. The diameter of the silencer system and the silencer box application and location is a common fault we come across often on systems we simply call “cheapies”.
This is the term describing the removal of one or all catalytic converters or particulate filters on all turbo models.
There is the perception that a cat is highly restrictive and its removal results in huge power gains. Think again. This may be the case when the cat has failed or broken, in which case it should be replaced or removed depending on your budget.
It is however not so simple. More often than not, the simple replacement of a cat by a straight piece of pipe will result in a very tinny metallic exhaust note (a pet hate which is almost as bad as an incorrect twin tail pipe installation causing a hollow or whistling Sound – THE Pet Hate!) A proper “de-cat” would therefore include the complete down pipe and possibly a Cat-fooler or software upgrade, depending on the type of vehicle in question.