[baz-r]

Originally Posted by voucht

Hi,
I have to disagree with that. I remember in the 90's we use to sell a lot of catalyst converter replacement tubes (called “Tube Afrique” in France, I never really understood why ). They were just empty tubes, and came with a bossing for the lambda sensor when needed. The belief was that a catalyst slows the exhaust gas down, and eats part of the engine's power. Friends of mine have a company (ECU and chips manufacturing) with a dyno bench. In 1999, they put a customer's unmodified Renault Megane 16V on the bench, first with the original cat, and then with the cat replacement tube. Guess what happened ? The car had more torque and power with the original cat than with the replacement tube. Why ? Because this car has been designed from the beginning for running with a cat converter. So replacing the cat on an “old” car (VW Golf 2, Peugeot 205, Renault Clio 1 and 2...) which engines and exhaust pipes were not designed to run with a cat might be a bit efficient (but the gain is never extraordinary), but on an engine which has been designed for complying with the emission regulations, most of the time it will not give you any benefit.
Just my little experience, but no offence of course !
Bye

its a simple case of back pressure and mapping to suit it