De-Cat the cheap way

Tool's needed:
Bandsaw/Hacksaw
Angle grinder w/ metal cutting disc
Welder of your choice (I used a TIG)
2 x Vice-Grips
Vice makes things easier
14mm Spanners +/Socket set to take out the downpipe

Step 1:

Take off the turbo heatshield, take out the downpipe - 6 x 14mm bolts/nuts from the back of the turbo, and where it's connected to the centre section. Take out the Lamda sensor or disconnect the wiring from the engine bay near the boost solenoid.

Step 2:

Cut the downpipe, heatshields and all, in half



Step 3:

Rip out all the crap inside, I used a screwdriver and hammer to prise it out... and cut off the heatshields around the cat with an angle grinder...



Much better



Step 4:

Clamp the two ends back together... make sure you don't have it on back to front before you start welding




...and get welding



Step 5:

Paint, if you wish...

Galvinising spray:



High-temp Paint:



Step 6:

Heatwrap the downpipe and put it back on...

Step 7:

Do the same to the centre section silencer if you wish, I did, no pics though

Et voila

 

Nice one! I big **** you to the CAT, like it..

 

nice job i was going to do that to mine but got a h&s downpipe so cheap i put that on on the end, would it not been a good idea to make it a open mouth while you had it off as that seems to cause quite alot of restriction, just an idea

 

It already was open mouth? As in there was no split in the pipe to begin with...

 

cool,did my 5" rear box today so this is next tuesdays project,lol,cheers!!!

 

What do you do at MOT time?

 

Cheeky "so 'n' so" - people like me spent ages designing 'all the crap inside' getting the right size of brick & density of cells, testing different wash coats, not to mention the holding mats and wire mesh supports... I dunno, "here I am brain the size of a planet"... LOL

Mick

 

No split in the pipe, but the standard downpipe does not have an open section behind the turbo wastegate. This poses a severe restriction to flow when you're up to or above spool up point and the turbo is passing gas out of the wastegate. To resolve that you either need a "bellmouth" or twin pipe (seperate smaller pipe for the wastegate which typically rejoins the main exhaust perhaps 9" back).

With almost no exceptions, aftermarket downpipes address this issue and allow a decent straightish flow from the wastegate (some use splitters to keep it separate for a short while, others don't). Therefore, whilst bashing the cat out of the standard downpipe will be an improvement, it won't be nearly as big an improvement as a replacement (or modified) downpipe with a proper solution for the wastegate. This is why people don't often bother modifying the OEM downpipe; sorry.

 

How does it sound? I done this once on a BMW E36 320, and it sounded a bit echoey. If that makes sense.

 

It's a '95 Import, only Imports post 96 are subject to the stricter emmissions test.

Hades; I havnt put the downpipe back on yet, as I'm waiting for heatwrap and a turbo blanket.... I'll look into modifying mine to suit the actuator

Mick; is it your job? If it is then you get paid for it so (If not then each to their own in what they do in their spare time ) I'm sure there are plenty of people in the world who appreciate your efforts IMO in this situation it's 'crap' as it's getting in the way of my lovely exhaust gases

 

I think you'll find your wrong there. Just got mine serviced, and the mechanic said it was only the earlier 1992/93s that were tested like this....

 

https://www.scoobynet.com/scoobynet-...st#post6744451

Well if it fails I'll put in a cat once a year/ can't be arsed with that and buy a sports cat

 

I did the same thing to my DP about 5 years ago although I cut a flap in the top bend and removed the cat etc from there! I didn't have to remove the heatshields or anything else. It made a significant difference to spool and performance.

For the centre cat I just bought a s/h STi5 centre, which gets swapped periodically

F