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Cat And 3'' System Vs. Nocat + Genuine Exhaust''

Torques

By Torques,
in Engines & Forced Induction

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Torques Mentor

Torques

Posted
Posted

I need some input on what you people think causes less restriction.

I used to have a De-Cat + the OEM standard Nissan exhaust..

That was fine and the sound was great.

I changed this to:

De-Cat + 3'' Greddy Stainless Steel PEII (http://www.nengun.com/greddy/power-extreme-ii)

The PEII is not bad but I find it noisy and I need to do something about it.

I suspect that putting the CAT back in will reduce the noise ..

However what would be more restrictive ->

De-Cat with the Nissan exhaust

or

The OEM-CAT with the PEII

I have a 3.5'' Tomei downpipe and an HKS-Dump, so there is increased volume after the turbo.

Car makes about 270kw.

hypergear Grand Master

hypergear

Posted
Posted

between a 100 cell and de-cat, the difference is 10kws at 360rwkws. On the same time it also depending on the quality of cat, as I also had a 100 cell cat which I punched out that made 120rwkws difference.

sydking Veteran

sydking

Posted
Posted

between a 100 cell and de-cat, the difference is 10kws at 360rwkws. On the same time it also depending on the quality of cat, as I also had a 100 cell cat which I punched out that made 120rwkws difference.

the problems is you can tell someone to go spend $400+ on a good CAT so they only loose on on the 10kw or so over a stocker... Or spend $0 and De cat which really, Gives the best result from a flow point of view.

Legality aside, We are all old enough to make informed choices here. End of the day nothing will beat a straight through exhaust.

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

between a 100 cell and de-cat, the difference is 10kws at 360rwkws. On the same time it also depending on the quality of cat, as I also had a 100 cell cat which I punched out that made 120rwkws difference.

Hey do you want to tell us what cat that was (or PM me if you don't want to bag them publicly).
Torques Mentor

Torques

Posted
  • Author
Posted

Thanks guys,

Much appreciated ..

Anus aside ;) I am in the UK and for imported vehicles there are certain loopholes to get around the use of a CAT.

I will see if I find a higher flowing CAT and give it go ..

Torques Mentor

Torques

Posted
  • Author
Posted

How can I bolt a silencer onto the tip?

Do you mean a ristrictor by chance?

These look very silly and put a lot of back pressure into the system.

simple just get a silencer and bolt/ screw it onto the tip, if its too quiet, get a bigger hole drilled into it

Dan_J Veteran

Dan_J

Posted
Posted

yes same thing

most japanese exhausts have a hole at the bottom so u can slip them in and screw them on, and dont they look the best.......

better then what ever back pressure you were making with a decat and stock zorst

Torques Mentor

Torques

Posted
  • Author
Posted

Hey,

I am not too sure about this since I had one of these restrictors and the actual diameter of the hole in the restrictor

was about half the size of outlet area the standard zaust offered.!

So I am tempted to say that it builds up more back-pressure which is not so good.

The turbo spools up faster (due to more volume present after the turbo) but then the restrictor

stuffs the system up.

I had one of these:

http://www.raceinspired.com/p-6887-hks-inner-muffler-silencer-96mm-universal.aspx

And they look really silly with that little pigeon hole, don't you think?

Cheers. .

yes same thing

most japanese exhausts have a hole at the bottom so u can slip them in and screw them on, and dont they look the best.......

better then what ever back pressure you were making with a decat and stock zorst

Torques Mentor

Torques

Posted
  • Author
Posted

Yes,

I agree .. it's the worst possible solution.

(I removed that restrictor very quickly when I saw how tiny the diameter was)

Those silencers are not for serious use. They do exactly what you'd expect them to do. They quiet the exhaust down by strangling it. Anyone who expects otherwise needs a lesson in, well, just about everything.

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