Pre cat removal thread please.

[Alun450]

I'm going to be fitting a de catted y piece, can anyone explain/ direct me to a thread with pics of someone removing pre cats please. If I know what your meant to do and my mate does it, it should work.

Im thinking I nead a re map. Whats your advice gents.

[GasMunkey]

Don't need a remap

You want to get the lambda's out,

Then just a case of smashing them out, with any thing long with a hammer

[jojackson4]

I read on here about a blocke did it with the manifolds on the car smashed them out and then put pillow cases on the open pipe and started the car it blows all the st into the bags like a hover Ear plugs may be kneaded
You nead the landers out of the way or be very careful

[Alun450]

Cheers guys, no re map that's good then.

[Richard 858]

I removed mine with the manifolds in situ. Arm yourself with hammers, chisels, sacrificial long handled screwdrivers & anything you can use to hammer & jiggle away at the cats. Definitely remove the lambdas first & allow 3-3.5 hours for each side (yes, really !) This should also allow for the tea, swearing & "why did I start doing this" breaks. Once I'd removed the bulk of them I used an old but powerful vacuum cleaner with a flexy end to suck out debris that made it into the manifolds. Then I used a flexy drive & flap wheel on a drill to smooth out the cat housings before finally starting up & blowing out any remaining debris (makes the neighbours jump with no exhausts fitted !) After that refit lambdas & Y-piece & enjoy !

[Alun450]

Sounds good to me, cheers, I've got new manifold bolts, I'm thinking of removing manifolds to do it.

Has anyone done the job by opening up the pipes and then welding them up after cat removal!

With all cats removed is it going to be louder! Lol.

Seriously am I going to above 105 dec.

I'm 94 at the moment and really love it!

I'll always have my old Y piece if Im not doing trackdays!

Or ear plugs!

The things you do for power!

[chris1972]

I haven't done mine yet. Jamie was going to help me sort them, but as I'm going to do the manifold gaskets I may as well smash them out at the same time. It is worth wearing a mask and some gloves. The materials used for the cats are pretty toxic and contain heavy metals and carcinogens. Best not breath any of that crap in.

[Alun450]

Your not wrong there. A well ventilated garage too.

[GasMunkey]

Alun450 said:

Your not wrong there. A well ventilated garage too.

Fag in mouth whilst doing it to compensate for a well ventilated garage

[Alun450]

Alex, I can see me gaining 25 hp and having to use slilencers at the track! Do the cans slow you down, surely the pressure is less right at the back so maybe not to much. I'll ask Peter on Wednesday.

[chris1972]

If you do happen to swallow any of the stuff, wash it down with plenty of beer and you'll be alright!

[QBee]

X

Alun450 said:

Sounds good to me, cheers, I've got new manifold bolts, I'm thinking of removing manifolds to do it.

Has anyone done the job by opening up the pipes and then welding them up after cat removal!

I have had my manifolds taken off, cut open, the 4>1 unions welded and the manifolds resealed and put back on. I didn't have the precats removed this time, as I want to do track days and thought I would see what my car drove like with the cats first. However, it must be a lot easier to remove the precats this way, as you cut the manifolds around their fattest part. Your 4>1 unions may well be blowing anyway, so it's a chance to get them checked and fixed if necessary. The cost of the welder was £100.

Alun450 said:

With all cats removed is it going to be louder! Lol.

Seriously am I going to above 105 dec.

I'm 94 at the moment and really love it!

This was my main concern. Removing the precats only adds about 3-5 dB, and adds 5 bhp. Removing the main cat adds substantially more dB and more BHP. How many I don't know, but I can see it being critical for track day limits. Peter will know more.

I also worry about failing the MOT - yours is a 99 car IIRC

Edited by QBee on Tuesday 16th April 06:30

[Alun450]

Come on Anthony its a 2000 car. It's to late anyway I've already agreed to have it.

I had a Jag with sports exhaust, at 2100 revs the resonance was terrible.

I've been in Peters just down the road and i didn't seem concerned.

It's the neighbours I'm worried about.

This way at least I keep my old Y, i can pick and choose!

Peter has wrapped his up, not only heat dissipating but also must quieten it down a tad!

It's a must if you want speed/ power for little expense.

Anthony yours is quick enough I'd suspect!

Regards the welding, I'm sure mine blows at the 4 into 1 point so that's very relevant QBee.

I think thats what I'll do get them cut open.

[phazed]

Standard exhaust with pre cats out, about 94ish db.

Remove main cat, about 99-100 db.

I use the small inserts in the pipes on any long journeys as the 100 db noise is annoying IMHO. This brings it down to about 94 again.

I got about a 20 bhp hike with the main cat removed but of course due to age/ mileage, every cat will be different.

Alun, if you need a workshop/ garage to do yours you're welcome maybe we need another gassing and fiddling day as the weather is improving!

[Alun450]

Peter you know how to ring my bells baby. Steady now gents, yes a day in the sun fettling, be great mate. I've got a list that's getting longer no matter how hard I try,lol. 100bd that's not so bad, if I get an ounce of extra torque I'm all in!

Bloody washed and polished the paint off the car just about, forecast tomorrow rain! I was going to drive to Snetterton top down, fyling hat on, rockstar stylie. How fast do I need to go to be ahead of the rain, lol

[phazed]

Alun, BBC site says fine for tomorrow!

Just finished myself, roll on tomorrow!