Meaning: Cells Per Square inch
Explanation: Cells per square inch, specification describing the active surface area of a catalyst, the larger the number, the more effective the catalyst.
Usual values 400 ... 600 cpsi for ceramic catalysts, rather higher for metal catalysts.
Slip-on or bolt-on systems usually do not require an additional catalytic converter, since the standard catalytic converter is usually retained.
For retrofit systems within the EU, also only necessary from yoc. 2006.
Additional catalysts may have to be registered and retuned.