Cat mod

Clio Nabz · Jan 17, 2017

Hi guys, I have a decat on the car at the mo but it makes the noise a little too loud so was thinking of putting the cat back on but I've seen there is a company BTB who can cut out the restriction on it, any body got this done before? I've seen on here they can weld a new front pipe onto it but I'm not sure if that was because it had a new system from manifold back, so they just normally cut the restriction out and buy a wider piece back in? Also is there anywhere else that does this?

Mikeyjp · Jan 17, 2017

ktec have been doing it for quite some time, as have others. The last owner of my car had a ktec system fitted with the cat mod, and it is all good

Clio Nabz · Jan 17, 2017

I'll drop k Tec a line cheers pal

Clio Nabz · Jan 17, 2017

Is the restriction on the manifold side or towards the rear end?

PP200t · Jan 17, 2017

I believe it's at the rear of the cat, they get rid of the olive joint (where the gasket goes) and replace it with a straight sleeve section. Most exhaust places will be able to do it, call around some of the small places they'll be cheapest and probably more efficient and effective.

Tommo. · Jan 17, 2017

The 'restriction' at the rear of the cat was deliberate to reduce noise and retain heat.

I had it removed and sleeved, but only as I had problems with the original join leaking and this seemed the best solution.

I wouldn't say I noticed any difference in terms of power / drivability though.

M.C.. · Jan 17, 2017

I did mine a few years ago as the joint kept leaking and sagging I would not pay to have it done unless you are having problems but if you can do it yourself it is worth it.

herzog · Jan 22, 2017

M.C.. said:
I did mine a few years ago as the joint kept leaking and sagging I would not pay to have it done unless you are having problems but if you can do it yourself it is worth it.

View attachment 174983

My centre exhaust join part is broken (I dont know how Renault could design so s**t join), and I´m thinking to do something like you, can you tell me the diameter (internal and external) that you weld at the cat, and the diameter of the centre part, internal and external too.

Thanks

Ps: My english is not the best one :wink:

M.C.. · Jan 22, 2017

My exhaust is 2.5 inch so I just got a vernier caliper and marked the cat at 2.5 inch and cut the joint off and then trimmed it to fit some 2.5 tube.
Hope that makes sense.

bashracing · Jan 22, 2017

my solution was to make a resonated de cat out of a centre box from an RX-8, still as quiet as a cat but flow better and sleeves over the rear exhaust rather than in to it, (shiny one is rx8),
@Djw John your RB also has this same set up

Daz... · Jan 22, 2017

I really need something like this doing on mine.

leedsboy · Jan 22, 2017

bashracing said:
my solution was to make a resonated de cat out of a centre box from an RX-8, still as quiet as a cat but flow better and sleeves over the rear exhaust rather than in to it, (shiny one is rx8),
@Djw John your RB also has this same set up
View attachment 175498 View attachment 175499

Don't have any more of them RX8 ones knocking around do you? Need to sleeve mine and that seems like a good idea.

Thrust-Rated · Jan 22, 2017

I had mine modified about 4 years back. It was chopped just above the lambda sensor port. I'm sure mine goes over the centre section not inside it. I may be wrong though.
Can't say I noticed any difference with performance, it was done because olive flange on cat pipe was knackered.

bashracing · Jan 23, 2017

leeds2592 said:
Don't have any more of them RX8 ones knocking around do you? Need to sleeve mine and that seems like a good idea.

not currently but will keep an eye out

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herzog

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