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Discussion Starter #1
Well, yesterday saw my first trip to Abbey Motorsport, and well worthwhile it was too. Only went to pick up an HKS wiring loom for my turbo timer, but ended up with the solution to a problem thats been driving me nuts, and a Cat replacement pipe which I am well pleased with.
At least, it looks great on my hallway carpet, but should be on the car later if I can persuade the Cat to come off.

My question is this.....

Most people have told me that there is a performance gain to be had by removing the cat, and it seems like a logical argument to me.
Then, last night I was drooling over parts on SVS' website and their theory seems to be that replacing the cat results in little more than more noise (which is fine with me).

Anyone got a definitive answer?

The car's stock apart from a Blitz Dump Valve (as far as I know anyways cos only had it a month or so).


Cheers
 

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Ho ho

I had a similar decision to make, and after discussions, decided to retain the standard cat. I have A'PEXi induction, HKS downpipes & a HKS Dual Drager exhaust.

The logic from my enquiries: Keep standard cat for low end torque, replace with a high flow cat or de-cat pipe for high end.

Works for me. Had a comment from a 550hp/400ft lb Skyline driver about how quick mine was off the mark when we were having a little blast.

In all fairness, this is a minority opinion at the moment.
 

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Discussion Starter #3
Cheers mate!

500BHP is just a tad out of my Puny RB20DET's range I fear! Goin to fit an induction kit of some form in the next months or so, for the meantime I'm just off out to get soaked and fit this pipe and see how it goes. Can always remove it I guess if I don't like it, sure someone would take it off my hands. Mind you, if it sounds good I might just keep it on anyways :)

Sad, I know...
 

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Discussion Starter #5
cheers

thats what I was hoping for. Just rang Abbey again to see when they can fit it after almost drowning myself in the puddle under the car today. Am confident it will be a good bit of kit in some way or another cos they obviously know their stuff.
 

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Ok, I decatted my GTR last weekend. I have no idea whether power and torque are up or down or whatever, and I don't really care.

The thing you do notice is that the engine picks up smoother, and comes on boost earlier. This translates into much better feel driving; and it certainly feels quicker because of that.

Its not much noisier than with the cat (i have HKS SPF, HKS Super Drager II), apart from a throaty roar above 5000 rpm. You only hit this when you're driving hard, so the noise here is really not important.

I would honestly and strongly recommend decatting your car. For off road use only, of course. >>cough<<.

Don't forget, catalytic converters are expensive. You can safegaurd your catalytic investment by taking it off and putting it in a cupboard, thereby ensuring that it's always in tippety-top condition.
 

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Discussion Starter #7
Whooosh!

Well,

The De-cat pipe is now installed, after lots of swearing and standing about. Been for a blast up the Motorway (always within the speed limit ;) and am quite impressed. The car is more responsive (for a 12 year old) and does sound a little more aggressive, so overall, it was a bargain at the price. Can't wait to get the induction done (once I replace the rear shocks :( ).

So... Thanks to Abbey for providing me a top bit of pipework, I'll be back.


:smokin:
 

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Where did you get the replacement pipe from? How much was it?
You also said " if the pipe is designed correctly, you will get the best of both worlds" By this do you mean it is a very good fit and not leaking any exhaust gas out from the joint? Or is there different ways in which a cat replacement pipe can be designed? As far as I knew it was just a straight through pipe.
 

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Discussion Starter #9
I assume

part of that post was for me. Abbey Motorsport provided the pipe and gaskets (no leaks!), its made of stainless steel. Gas sensor plugs straight into it so that still works (if it ever did). Simple case of removing the heatshield from existing cat, unbolting cat and swearing at it and using a can of WD40 while burning your hands to remove cat. Then, bolt in the replacemnet.

Technically its just a straight bit of stainless with a bit for attatching the sensor, but I reckon there's a bit of though to the design/manufacture.

As far as price, call abbey and ask them as I got mine as a second hand one from them so I can't say what a new one costs.

Pipe adjusts airflow thru system, hence backpressure to the engine, which (the correct amount of) is important to the engine's running, so any old pipe may not increase performance. In fact, it could decrease. It does sound good though, so even if performance hadn't changed (as long as it didn't decrease) I personally would have kept it on.
 
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