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Oem cat restrictive? Solution.....

devil84 said:
But surely an aftermarket manifold is more free flowing than Oem despite retaining a cat??
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It would have to follow the same shorty 4-1 design to be able to have a section for the cat like the OEM.

A full race header can have a proper 4-2-1 design with secondaries that a stubby design cannot incorporate. It's the uncompromised arrangement that leads to most of the gains. Pipe diameter also obviously helps.
 
Okay cheers guys, will have a think then. May just the k100 mapped to my current mods of a 60mm catback ad itg induction kit.
 
Loxy said:
It would have to follow the same shorty 4-1 design to be able to have a section for the cat like the OEM.

A full race header can have a proper 4-2-1 design with secondaries that a stubby design cannot incorporate. It's the uncompromised arrangement that leads to most of the gains. Pipe diameter also obviously helps.
Click to expand...

Been doing more research into this, but that shorty manifold I linked was a 4-2 design, so by implication, by adding a sports cat pipe on to this 4-2 mani, it is therefore a 4-2-1 sports cat manifold??

Does it work like that? Surely that combo above, is the same as a Piper Mani with sports cat?? what else would I be missing lol

To put this into context, I would be mapping this either way, current mods are Supersprint SIlenced B pipe, 2.5inch bore backbox, and ITG intake.
 
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the 4-2 mani looks to be a 4-1 mani but with a plate in the middle

where as a 4-2-1 has physical spaces between

piper with sports cat has longer runners than oem, just a stubby cat section
 
thanks guys - food for thought. Cheers JamesT, appreciate the money saving advice! Hope you are still liking your backbox mate :)

I just want good pound for pound mods, I think the K100 with my current mods will get my car to a very nice place already, and I should not carry on chasing extra ponies.... especially when the advice on here is pretty unimanous. :)
 
Ah I only ask as I was looking at the same setup myself with a Buddy Club Cat Back after the JapSpeed Mani & High Cat lol
 
Did anyone ever go for this setup, considering it myself? I understand that without a remap I would not see the gains but I'm happy to stay 'OEM' just with an upgrade to SS.

Would it be safe to run without a remap, possibly with an O2 spacer, as I'm not looking to go down this route any time soon?

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o2 spacer does NOT make A/F ratio safe, only trick your ECU into thinking it is so it doesn't display an EML on the dash.

It is strongly advised that you get a remap if you changing the OEM cat to anything but OEM spec.
 
And as said a 100cell cat wont pass mot, the piper cat (one of the best aftermarket cat options) mentioned is hit and miss to pass when really hot.

If you are going to the effort of swapping the mani, might as well get the most out of it and go 4-2-1
 
Hazz said:
o2 spacer does NOT make A/F ratio safe, only trick your ECU into thinking it is so it doesn't display an EML on the dash.

It is strongly advised that you get a remap if you changing the OEM cat to anything but OEM spec.
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And what about without an O2 spacer, only negative that EML displayed?
jimbodeeni said:
And as said a 100cell cat wont pass mot, the piper cat (one of the best aftermarket cat options) mentioned is hit and miss to pass when really hot.

If you are going to the effort of swapping the mani, might as well get the most out of it and go 4-2-1
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It's actually a 200 cell cat mate.

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TuckR said:
And what about without an O2 spacer, only negative that EML displayed?

It's actually a 200 cell cat mate.

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Click to expand...

Hazz said:
o2 spacer does NOT make A/F ratio safe, only trick your ECU into thinking it is so it doesn't display an EML on the dash.

It is strongly advised that you get a remap if you changing the OEM cat to anything but OEM spec.
Click to expand...

^^ THIS ^^

I wouldn't bother, you be lucky to get an MOT pass out of it and wont make that many gains with a map.
Get a 4-2-1 + remap or leave alone IMO.
 
Fair enough, obviously if it requires a remap then it's not worth it as I may as well go down the 4-2-1 in that case, like I said I'm trying to avoid that.

My OEM cat doesn't look like it will last much longer which is why I was considering this as a replacement. I assume a new one will be extortionate & a used one will be pretty much the same condition as mine by now. I'm not keen on using an OE spec one, ECP have a 'React' branded catalytic converter for sale but I can't be sure that it's built to the exact same specs as the original anyway.

Hence my hoping this would be a case of swap and go whilst 'upgrading' to SS in the process.

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It might look rusty but they're pretty substantial castings, it'll be fine. The core will likely go before the casting. If it ain't broke....
 
Thanks both, I hear you loud and clear. I'll leave it alone until it dies!

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TuckR said:
Fair enough, obviously if it requires a remap then it's not worth it as I may as well go down the 4-2-1 in that case, like I said I'm trying to avoid that.

My OEM cat doesn't look like it will last much longer which is why I was considering this as a replacement. I assume a new one will be extortionate & a used one will be pretty much the same condition as mine by now. I'm not keen on using an OE spec one, ECP have a 'React' branded catalytic converter for sale but I can't be sure that it's built to the exact same specs as the original anyway.

Hence my hoping this would be a case of swap and go whilst 'upgrading' to SS in the process.

Sent from my SM-G935F using Tapatalk
Click to expand...

I was in the same dilemma, when i fitted my cat back exhaust the flange that goes from the cat to the b pipe was corroded.

So i made the decision just to buy the japspeed decat pipe. Cat should be ok for MOTs.

Got it for £69.99 off ebay and then had to spend another £5 on new spring bolts as they only supplied the donut gasket for the manifold side and the metal gasket and 3 replacement bolts for the b pipe side.

EML has now came on but i will be getting either k100 or kpro once i have the funds to do so.

Bear in mind if you go for a japspeed 4-2-1 manifold you will have to get uprated engine mounts or engine mount inserts. If you don't the flexi will last 18-24 months tops.
 
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