CAT BYPASS

[Sport182]

Right i have decided to forget getting a new CAT and buy a K-TEC or Magnex (yet to decide) bypass system.

However does anyone know if this will effect my MOT and whether or not i can just unscrew a section to put the CAT back once a year just for the MOT (if you understand what i mean)??

 

[Griff]

Dont mention it at the MOT station. Its a free retest after all so you may aswell try the test with the decat in place first. I know a few cars have easily passed the emissions test with a decat in place.

 

[Dash]

What is a " realistic "( ie not Saxo figures ) performance gain in using De-Cat?

 

[Clio16vPaul]

when i asked the same question, i was told that id lose alot of torque and basically gain a bit of top end power, so i chose not to bother...

However, as for the original question, if the car passes the emmissions test without it then fair enough but apparently its unlikey to cos the test is far tighter??

 

[Chris_H]

on the mk1 172 you should be ok as its pre 2005 emmisions thingy so it should only have 1 lambda probe. The mk2s will not run right, as the 2nd sensor is after the CAT to check the cats doing its job.

You will not lose a lot of torque and gain power.

You will only really notice a difference in revving as it should rev freer. Maybe gain you a few bhp. It really depends on the entry and exit tapers of the existing CAt and its cell count thus how much flow restriction and turbulence it cause. The more trouble it causes the bigger the gain at the top end but it may cause a loss lower down due to overscavenging.