The particulate filter is a stand alone unit. It is located upstream of the cat in the exhaust system and its purpose is to remove soot particles from the gas stream. The cat the proceeds to do its usual job of converting CO to CO2 and is in no way dependent or relied upon by the particulate filter.
In diesels the cats are two way devices and run in unregulated mode (ie. no O2 sensor like a petrol car).
Alloy wheels and their impact on handling and performance.
Some rally style alloy wheels are lighter – (less weight = more speed) and also are designed to increase the cooling of the brake disks.
Some designs hold up better to being curbed than others and some break very easily when hitting a pothole or curb at speed.
Always go for the best quality alloy wheel that you can afford and read the reports and reviews. If you do go for a different overall size you must get the suspension and tracking realigned to avoid uneven wear under acceleration.
Vents – adding performance with Bonnet vents.
Performance gains are possible with the addition of bonnet vents.
Warm air really does kill performance. This is due to the air intake temperatures being hot and air at high temperatures carries less oxygen.
When driving an engine hard the under bonnet temperatures quickly build up and the engine has no choice but to suck this air in reducing your power.
Low ratio sport gearbox setup and selection.
Gearbox – Lower ratios give better acceleration times and lower fuel economy. Six or seven speed boxes are better matched to modern engines.
Most street applications are closer 1st and 2nd gear ratios for that off the line 0-60 boost or for the fast exec a lower 2nd and 3rd ratio give improved overtaking flexibility and 30 – 70 mph acceleration with a high 4th and 5th gear to give motorway fuel economy.












