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Old 04-14-2004, 10:58 AM   #16
Machine Age Victim
Scooby Specialist
 
Member#: 29961
Join Date: Nov 2002
Chapter/Region: South East
Location: my job is a hobbie to most
Vehicle:
2008 BMW 328i Conv.
2001 Kawasaki ZR-7S

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Quote:
Originally posted by Top_Dog
I ran a highflow last year and it made a difference. I will be looking to get the Stromong catless track pipe for track days.
Quote:
Originally posted by Opie
Actually going cat-less will reduce HP compared to running a stock or High-flow cat on a computer controlled car. Few reasons why; not enough back pressure, ECU "correcting fuel and air mixtures to try and compensate, etc.

I did a year of testing on this subject back in 1996 for the comapny I worked for; Gordon-Darby. We had consistent dyno test results that computer-controlled cars saw a reduction in their HP readings and mileage after removing the cat compared to the stock cat. We also tested a few high-flow cats at the time and saw that those, depending on brand/style, provided minimal HP gains yet still reduced mileage all with acceptable emission levels. Without re-programming a car's ECU to compensate for the removal of a cat, those that are claiming gains from doing this are making these claims via "butt-dyno" testing, not and repeatable or consistent testing method such as a dyno.
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