2nd decat only removal - still need restrictor?

[Pete]

I'm in two minds what to do.

Tomorrow the 2nd CW decat pipe comes off the SZ and has the cat put on.

 

I either wait until I can get the first decat pipe from Chris for the VVTi and have the restrictor ring all fitted together.

 

OR

 

I impatiently stick the 2nd decat on keeping the first cat for the moment. Will this cause me problems with boosting high and fuel cut etc without a restrictor ring?

 

Has anyone compared the difference between just one cat and no cats? Am I right thinking it's the 2nd cat that does most of the work?

(By 1st cat I mean the one closest the manifold)

 

Ta.

[Scoboblio]

I think that the 1st cat, closest to the turbos is the most restrictive, from other people's experience I think that 1.0 - 1.1 bar is usual for removing just the 1st one - so I can't see it being any higher when removing just the 2nd.

 

I suppose if you have problems with overboosting it will just hit the fuel cut anyway and not cause any damage - with one cat in you'll probably be getting very close to fuel cut in this weather (mine's currently hitting over 0.9 bar with BOTH cats in and a FMIC ).

[Pete]

The weather change is a worry.

My car is stock with no custom IC. Maybe I'll give it a go.

[hadyn]

You wont get more than 1.2 bar with one cat in place.

 

Mine makes 1.1 bar tops in cold weather with a restrictor ring in and no cats

[Chris Wilson]

It won't over boost if the 1st cat is still in place with one of my 2nd de cat pipes behind it and no ring.

[Pete]

Cheers Chris.

Sadly didn't get the decat off the car today...yet still somehow managed to get through the MOT!

Ah, bless 'em for sorting me out...

I'll have to get it off though and onto the VVTi.