DE-CAT PIPES

[jonny tvr]

I've previously had a Cerbera which I had de-cat pipes put on in place of the cats. The performance and noise were better (noise particularly). I have a 99 Griff now, the noise is great but its not as good as I want and I prefer the idea of no restrictive cat converters on. I've done a search on the forum and unless I've missed it(possible) I can't find anything on this. Anyone have any ideas? Jon

[fastandcurious]

How did you manage at the MOT without cats on the Cerb? I like the idea of getting an even better sound out the Griff. But the sound can be vastly improved by leaving the cat and pre cats in place and going for a mod on the silencer box, ie bypass it with two Cherry Bombs or staight pieces of 2 inch tube. I am considering doing one of these mods myself, but I fear the latter me be a bit to noisey.
I'd be interested to here from anyone who has done eather of these mods, and here whether they are pleased with the results. The Sunset pearl Griff on Youtube sounds great. Is that anyones on here?
Cheers CRAIG

Edited by fastandcurious on Saturday 10th February 19:23

[clive f]

on getting my griff last year the first thing I did was to remove the perforated pipes in the silencer and replace with straight through pipes, this was a little better, but still did`nt give the desired effect, I have since removed the precats, this has helped a lot, its a happy balance between hearing the lovely v8 burlble and the pops on the over run, and not so loud that you cant have a chat with the mrs, although I sometimes wonder if that is a good thing or not?

I`ve heard several cars that have been de catted and they do sound superb, but not sure on how this is on motorway cruising etc.

[fastandcurious]

clive f said:

on getting my griff last year the first thing I did was to remove the perforated pipes in the silencer and replace with straight through pipes, this was a little better, but still did`nt give the desired effect, I have since removed the precats, this has helped a lot, its a happy balance between hearing the lovely v8 burlble and the pops on the over run, and not so loud that you cant have a chat with the mrs, although I sometimes wonder if that is a good thing or not?

I`ve heard several cars that have been de catted and they do sound superb, but not sure on how this is on motorway cruising etc.

Does removing the pre cats affect emissions at the MOT. What are they made of. Are they monolith or just perf tube with glass fibre round?

Edited by fastandcurious on Saturday 10th February 21:15

[David H]

Does anyone know of a company that makes a de-cat Y-piece? Not just a standard dustbin with the cat removed but a proper smaller bore jobbie. I know ACT do one but I am loathed to pay their £290 delivered price (can get a whole system for most cars for that price!)

The ACT one:

[clive f]

[pic][/pic]

this is a pre cat, I removed mine by cutting the pipe, and welding it back up once the cats were removed, okay as long as you mark the pipe in several places so as to re-align it, some people manage to drill and bash them out from the open end of the pipe.

I had mine mot`ed today, and there was no problem with the emissions test what so ever.

[clive f]

David H said:

Does anyone know of a company that makes a de-cat Y-piece? Not just a standard dustbin with the cat removed but a proper smaller bore jobbie. I know ACT do one but I am loathed to pay their £290 delivered price (can get a whole system for most cars for that price!

I make this sort of thing myself for a living, and it is time consuming, and stainless steel is a very expensive material, if I wanted one I would rather buy one from Act, than spend my own time messing about, I think its a fair price.

where can you buy a stainless steel system from for a v8 for less than that??

[David H]

clive f said:

David H said:

Does anyone know of a company that makes a de-cat Y-piece? Not just a standard dustbin with the cat removed but a proper smaller bore jobbie. I know ACT do one but I am loathed to pay their £290 delivered price (can get a whole system for most cars for that price!

I make this sort of thing myself for a living, and it is time consuming, and stainless steel is a very expensive material, if I wanted one I would rather buy one from Act, than spend my own time messing about, I think its a fair price.

where can you buy a stainless steel system from for a v8 for less than that??

I said most cars Clive, not apecifically a V8. Something like a Mongoose system (decent quality) for a hot hatch starts at around £225.

I would also not make a one off for £290 but ACT are not producing it as a one off! Anyway, I'm not here to have a dig at ACT I was just asking if anyone knew of an alternative supplier.

[uncle fester]

What was the purpose of the pre-cat's? I assume they were fitted for a reason, so what is the downside of removing them?
Can anyone post a diagram of the exhaust and its internals please?

[bluebottle]

uncle fester said:

What was the purpose of the pre-cat's? I assume they were fitted for a reason, so what is the downside of removing them?
Can anyone post a diagram of the exhaust and its internals please?

Pre cats were fitted becuase it was feared that some engines would not pass the cold start emissions test. As test centres don't do cold start test (mainly cos you just drove it there) it wont be a problem.
Benefits are that it improves the engines breathing and the side effect is improved exhaust tone.

[fastandcurious]

Does any one know what effect all this de pre catting an messing about with the exhaust has on the performance. It would be a shame to go to all this trouble only to find problems in the keeping up with the Cerbs dept

[jeffsy]

jonny tvr said:

I've previously had a Cerbera which I had de-cat pipes put on in place of the cats. The performance and noise were better (noise particularly). I have a 99 Griff now, the noise is great but its not as good as I want and I prefer the idea of no restrictive cat converters on. I've done a search on the forum and unless I've missed it(possible) I can't find anything on this. Anyone have any ideas? Jon

Jon

Iv sort of tried most things now

- Standard Griff 500 standard zorst - nice
- Standard Griff 500, straight through pipe - v v nice (111 Db at last years Growl)
- Non std Griff engine, straight thro pipe - - v v v v loud - it kinda made its own weather . Got stopped by plod for being too noisey sooooo I got...
- Non std Griff engine, ACT quad zorst with cherry bombs - nice noise but no where near as noisey as the one above. Probably for the best I reckon as I dont want to be looking over my shoulder too often

My straight thro pipe zorst is up for sale if you want to drop me a line. Its in good nick (I even have the silencer box to throw in as well if you wanted it!!) - the only reason I changed it is my new engine is rather louder than the old one

cheers

Graham

[jonny tvr]

Thanks for all your advise. I think I will go straight through pipes to replace the silencer. This way there should be no probs at MOT time, 111db sounds just right and it sounds like an easier job ... also may be a bit of weight saving looking at the huge silencer.

Graham,

Interested in your pipes .. how much do you want and can you post?

Jon

[Paul V]

I had the pre-cats removed on mine a few years ago, recently had the silencer sleeved by TVR power too. I have a video of it on www.sportscarpages.com under my videos quality isn't great though as taken with my phone.

[adyw]

My no longer required Y piece without the main cat is on E bay if anyone is interest, makes car louder, but won't pass the MOT.

[Big Ashy]

Link to pre cat removal www.pistonheads.co.uk/gassing/topic.asp?t=352250&f=8&h=0

[jeffsy]

jonny tvr said:

Thanks for all your advise. I think I will go straight through pipes to replace the silencer. This way there should be no probs at MOT time, 111db sounds just right and it sounds like an easier job ... also may be a bit of weight saving looking at the huge silencer.

Graham,

Interested in your pipes .. how much do you want and can you post?

Jon

Jon

YHM

cheers

Graham

[IPAddis]

adyw said:

My no longer required Y piece without the main cat is on E bay if anyone is interest, makes car louder, but won't pass the MOT.

Link? Can't find it.