How is it done , can anyone help me? I is attached to the flange going onto the manifold.
A right pig of a job mate
Its all part of the downpipe/cat, what you need to do is remove the cat from the manifold, put it in a vice then get the gas and air on it, once its glowing, start with an air chisel digging it out. Theres no other way ive found to remove them. Once you start digging you'll find the pre cat(wire gauze) is about 4" deep!
So it takes a fair while heating it then chiseling it.
Once youve dug all the centre out, get all the gauze thats left round the sides out, and give the pipe a damn could clean out as you dont want any of the crap going into the cat.
Emory cloth the sides aswell til theyre smooth.
I must warn you mate, its a bitch of a job to do and if your not that mechanicly skilled, leave it to a pro.
Removing it makes a noticable difference in power, i had the car on the rollers at AmD before i did mine and then after and it give me around 7bhp, and then i had my map done straight after.
The exhaust also sounds a lot better now as the car isnt struggling to breathe!!!
If you need any more advice chap drop me a pm, as i think im the one of the few people that has done this mod.
One of the lads in the vxlscc club removed his precat in the same way, Unfortunatly when we had it on the rollers at a recent RR day, my box standard 2.2 put out more power than his de-cat 2.2 did. Sounds like a lot of effort for no gain to me.
The problem with de catting the 2.2 in this way is you loose air speed in the exhaust and the bore of the pipe suddenly grows to around three inches inside the box and then down again.
To bypass properly you need a pipe put in of the same bore as the system.