Steve vRS

Has anyone done this?

What I mean is removing the up pipe and centre cats but leaving the OEM downpipe in place. I know the downpipe cat is the largest but I have read a few posts detailing strange happenings on MY01's following a full decat and TSL recommend leaving the downpipe cat in place.

Would (does) it make a marked difference in the cars performance, not only in top end power but in driveability and will all the various exhaust gas sensors be happy and not generate spurious fault codes?

Thanks in advance

Steve

yoza

Yes this is what Ive done,
Re-moved the cat from the mid section(opened it up like an easter egg,then re-moved the cat and welded it back up again).Also added a G.Goode back box for much loudness.
I have no CEL light problems and it will pass an MOT.Also cutting the cat out of the mid section is discreate,when you look at the exhaust from below you cant tell its de-catted,it is also covered with a heat shield so you cant see the weld.
Later Eboneezer Scrooge.

PS anyone got a catted up pipe they dont want(original for my01)Thinking of doing the same to that,see what the gains are like.

Steve vRS

Yoza,

What I meant was has anyone removed both the up pipe and centre cats?

Steve

Pete Croney

Steve

If you remove the up pipe cat but keep the downpipe one, you will still get error P0420 as the ECU needs both cats for its check routines... unless you fit a rear O2 signal modifier.

If you are going to fit an O2 fix, you would be far better to change the downpipe and keep the up pipe cat. Its a LOT less work and the downpipe makes the biggest improvement of all.

Ru$$Rip

Yoza - When can you de-cat my centre for me??? Buy you a pint!

ZIPPY

Do as Pete suggests, the down pipe transforms the performance in conjunction with the centre and back box.
Yoza (Cheapskate)tell them how long you had a bad chest for when you attacked your centre section with a cutter,(lets see if i can blow through that honeycombe section).

Zippy

Rice Rocket..

I only have the up-pipe to do (next week), but i thought that it was the up-pipe that held the car back more than the down-pipe!!

What do I know, I only throw money at her anyway


Rice Rocket

Caronte

Pete,

keeping the uppipe only is a real danger for the integrity of the turbo. It can easely brake and the bits and pieces end up in the turbo. Worth removing everything.

Andrea

yoza

If anyone is thinking of chopping out a cat use the correct mask,coz it gave me a bad chest for two weeks

It didnt help when I decided to blow through it a few times to see how restrictive the air flow was.

Russ when I get the time Ill do the spare one Ive got then Ill have your catted one in exchange.

Later Yoza

rich uk300

guys be careful of a full de-cat....had one done at scoobysport,sounded great and increased bhp and torque...so everything was hunky dorey....wrong,had defi gauges fitted and my boost was holding 20 psi...not good...went to power engineering who sorted problem out,but at a loss of power...they were a bit concerned to say the least

raybotha

The uppipe cat only gives prob's if with higher boost . I know guys whose turbos have eaten most of the cat and that turbo is whining happily away . I think we forget how hardy a turbo is . Changing your restrictor will cure those spikes anyway . I have had great fun with a an industrial bleed valve (the thing you turn)installed in place of the restrictor which allows you to get it just right . Interesting to see on road performance against another car while doing this . Those spikes really help performance ! I'm all for home made improvemments , but inevitably you land up spending twice as the Scooby sport beckons . I plunged out my centre cat too and it does help . The downside of decatting the downpipe is the echo chamber sound effect you get afterwards . I didn't like it . Sounded cheap and nasty .

Good luck
Ray

Steve vRS

Rich,

Can you expand on your tale of woe?
Mail me if you don't want the problems in public.

Steve

rich uk300

steve....

not much more to add....just that power engineering were quite sure something would have melted in the end if i had not wound the boost down...it was lucky i had the boost gauge fitted else i would of never known..it was a full decat scooby sport system including up and down pipe on a uk300...hope this helps

cheers

rich

Steve vRS

What had caused the boost to rise? Was it purley the de-cat or did you have a dawes or other boost controller?

Steve

rich uk300

steve.....it was a uk300 with ppp...no other mods,scoobysport full exhaust added and hey presto 20psi 1.5 bar,mervyn from p/e brought it back to a sensible 1.1 bar....he stated whilst he was testing my car on the r/r that he was worried when my car registered these figures.....must admit i was unhappy at first with reduction of bhp and torque figures once restored to 1.1bar...but at least i knew nothing was going to go pop

Floyd

iTrader: (9)

Yoza, yeah don't do it without a mask, not sure what all those precious metals will do to your innards! Oh and you can de cat it without cutting it open.

F

mark@wrx

Steve, do you remember Dan from Croft? Had the silver MY01, He was saying that after he replaced the exhaust he was getting 1.5bar! Don't know if he got it sorted.

Pete Croney

Hi Rich

I'm surprised to read this, as we have done the same to lots of PPP cars and they hold the same 1.2 to 1.25 bar as before the work was done.

One of our staff cars has the same set up. It has been on track several times and has seen over 160mph a couple of times (German autobahn, of course).

I suspect that your dealer may not have changed the boost control restrictor when fitting the PPP, hence why you were seeing 1.35 bar.

1.1 bar is low for a PPP car and you will be loosing a lot of performance.

Pete Croney

Also Rich, we have no info as to what boost you were running before the exhaust was fitted.

Steve vRS

Pete,

I am running exactly 14psi at the moment. If you give me a full system I will see if the boost changes

I'll also put a Scoobysport sticker on my Scoobysport spoiler for you. Now that's generosity for you

Steve

Pete Croney

LOL

I'll toss a coin Steve. Sorry M8... tails

WRXBOB

I'm booked in at Scoobysport on Tuesday for fitting FULL de-cat to my motor(my02WRX)
Got NO worries about it

I'll report back next week...

Bob

rich uk300

pete.....let me get this straight at the start i'm not having a go at your system or how it was fitted,bunch of nice guys and quality fitting and service(thats enough sucking up)

i was well suprised with readings at 1.5 bar,boost readings were not checked prior to your system being fitted,so problem could of been there already....all this seems to prove is to have gauges to keep a check on what your engines doing,as i think my car wouldn't of kept running at that level of boost for too long

Pete Croney

Hi Rich

I agree and its a difficult situation. The problem with a PPP car is that you need to fit a propper boost guage to check the boost, rather than just plug in the Select Monitor. It then needs to be road tested in 4th and 5th. This is because the WRX PPP gives false boost readings to the ecu.

I'm sure that the fitting of the PPP includes road testing by the dealer and would expect that they had already changed the restrictor and tested the boost produced.

I was, at first, sceptical about the combination of the two products and we did a lot of testing with the first customer (a friend who insisted we try it). The results were spectacular and safe. We then tested all of the early ones that followed and the results were the same.

There's no right answer to your case but perhaps we should offer the option of testing similar installations, should the customer want us to. The long and short is that the PPP installation should be right, in the first place.

Scooby Dooby Blue

That'll have been all the asbestos and arsenic I packed it with before I sold it to you

Paul

nigel s

Rich / Pete, I have considered a full decat on my UK300 PPP. I fitted a boost gauge to keep an eye on things, my boost is up at 1.3bar and have seen 1.4. Will this increase when removing the up and downpipe. Have already questioned my boost levels with a very reliable source who advised me not to worry.

Pete Croney

Hi Nigel

It won't increase and boost control on UK spec cars is very good.

Your boost does sound a bit high for a PPP.