John McLaren

Hi all,

I've got a 2005 Scooby wrx and so far all i've got for it is a K+N panel filter. Now i'm looking at the exhaust.

I want to de-cat it, but after reading some threads, it looks like i've got more than 1 cat! Is this right? Or do i have 1 Cat & 1 silencer?

If i have 2 cats - i'd like to replace them with a straight through pipe. So can anyone suggest where the best place to buy some de-cat/s for my scooby.

Basically i decided not to get the PPP package and i want to upgrade my car bit by bit.

Cheers,

John

durry300

Hi John

I own a 2004 ver8 Sti Jap import- I've recently had the exhaust fully decatted- here's some advice for you- I'd recommend Hayward and Scott in Basildon (Essex) to supply the exhaust. They can also fit it for you if travel is convenient???

You have two cats on your current standard exhaust system- one on the downpipe from the turbo and one in the cat pipe section- fully decatting your car is a good idea but you need to bear in mind a couple of things:-

1. make sure that you re-insert the two lambda sensors on the new exhaust- one on the downpipe section directly behind the turbo and one in the cat pipe section.

2. be careful driving the car after decat and seriously consider a remap- with no cats in the exhaust the ecu will more than likely start dumping extra fuel (up to 25%) as the top lamda sensor will be reading differently- be prepared also for the engine cell light to light up on your instrument panel. This shouldn't be a problem if the car is driven conservatively but if you start using full boost then you run the risk of either running too lean (possible piston melt) or too rich (causing possible bore wash).

Take it easy to start with (don't exceed 0.5 boost) and contact a decent mapper for professional advice- i'd recommend Bob Rawle (BR Developments, Swindon).

I know there's lots of different threads giving conflicting advice but this is solely from my recent experience. I like to think that I did alot of research using professional advice.

Good luck- hope this helps!!??

Mark'sWRX

You've got 3 cats! One in the downpipe, one in the up pipe and one lower down between the downpipe and the centre pipe. The lower one is easiest to remove with a bypass pipe, the other 2 need a bit more work. I've gone for a sports cat downpipe and decat up pipe to stay legal but only loses 2 bhp (so they say).

Decat pipe can be bought from several places. Try Hayward & Scott, Scoobyparts or Scoobyworld to name but 3.

funkyspider

arent there 3 cats on a newage WRX ??

I also went for a high flow cat downpipe (the one fitted with the prodrive PPP pack to an STi). The centre cat is easy to remove and can be done cheaply leaving the other 2 for a slight gain without a remap. For the up-pipe I fitted a magnex slip jointed (wrapped). The slightly smaller diameter of the magnex helps early spool up on the TD04 turbo, although I agree with comments about H&S as that was my other choice.

If you remove cats from downpipe and the up pipe the you will need a remap. If you are doing one I'd recommend doing both at the same time. Decatting the up-pipe will mean removal of the EGT sensor (or relocating it in a boss in the downpipe) as it cant cope with the higher temps in the decat up pipe.