Free Flowing Cats

[robgt]

Has anyone fitted them. Apparently my car has 6 cats, when removed and replaced with 2 much smaller ones I can expect even quicker throttle response with an albeit small top end power gain. I would anticipate an obvious weight reduction plus a lot more V8 music. Would the warranty be blown. Thanks in advance.

[yeti]

I have them, but just the last 2 replaced with 200cpi units. Even that made a huge difference to throttle response, little bit of power and torque, noise is great, no downsides really!!

Are you proposing all 6 with just 2 or just the last two like me? From 6 to only 2 is what Bamford Rose do but will need quite a complicated exhaust set up, a lot of pipework and dealing with a load of oxygen sensors somehow. If you're thinking of replacing all 6 with 6 new 200cpi units then it'll cost a bleedin' fortune!

As to warranty... that's a a big question but you'd have to think 'yes' I'm afraid.

[DAMIT]

Do the V8V's really have six?

[yeti]

DAMIT said:

Do the V8V's really have six?

Yes.

Edited after Mike's post - no it doesn't and I apologise for being so sure of myself. I was confident the V12 did, no idea why I thought they'd be the same!

Edited by yeti on Tuesday 10th April 19:58

[yeti]

DAMIT said:

Do the V8V's really have six?

Yes.

Edited after Mike's post - no it doesn't and I apologise for being so sure of myself. I was confident the V12 did, no idea why I thought they'd be the same!

Edited by yeti on Tuesday 10th April 19:58

[DAMIT]

Just surprised thats all. Thought there were only two on this picture I guess lugs must be where the others are.

http://thumbsnap.com/vpnxKBpR

Learn something new each day!

[yeti]

DAMIT said:

Just surprised thats all. Thought there were only two on this picture I guess lugs must be where the others are.

http://thumbsnap.com/vpnxKBpR

Learn something new each day!

That's because that's the Bamford Rose modified exhaust system! Total manifold to backbox affair that has reduced the AML 6 catalyst system to 2 x 200cpi catalysts.

[mikey k]

Rob get the BR manifold back the AM rear box.
The let me hear it

[MadMacMcMad]

mikey k said:

Rob get the BR manifold back the AM rear box.
The let me hear it

This is what I had done at BR. What a difference. Performance and the sound is truly epic.

[yeti]

MadMacMcMad said:

This is what I had done at BR. What a difference. Performance and the sound is truly epic.

Looking forwrd to hearing that at Le Mans

We'll be a miniture Bamford Rose army down there!

[robgt]

Is the idea to just change two cats and if so at what cost? What gains would it achieve. Same applies to the exhaust manifolds. I'm sure doing the latter would mean bye bye to my warranty.

[yeti]

robgt said:

Is the idea to just change two cats and if so at what cost? What gains would it achieve. Same applies to the exhaust manifolds. I'm sure doing the latter would mean bye bye to my warranty.

Changing out the last 2 cats is what I did originally with DMS, simply because it's easy and can be done while you wait. Remove old, replace with new. BR's system is far more intricate and has taken them a lot of work to delete all 6 heavy and restrictive cats and replace with 2 x 200cpi units, huge weight saving of course as well as power/torque gains.

Gains just for 2 x cat replacement... hard to say. I had, all at the same time, 2 cats replaced (10bhp?), QS backbox (7bhp?), J1 air filters (5bhp?) and ignition timing changed for super unleaded (8bhp?) so hard to say what they did on their own. However, the difference in driving and throttle response was amazing, but as to actual power...probably nothing hugely significant on their own. I think BR Mike's estimate was probably close to 25-30bhp all in on my car, hence my 'guestimate' bhp figures.

If you do your manifolds and cats with the BR system, you'll get 40bhp and a slab of torque due to the cat deletion, though with it being an 'S', you may already have the upgraded induction?

Warranty... well if an electric window fails, they aren't going to argue! Why would an exhaust cause a gearbox or engine issue either? Talk to your apparently friendly dealer and sound them out. I'm sure the official line is no changes, but realsitically, changing the exhaust can't cause the aircon to pack up, I would imagine they have to legally honour the warranty unless they can show you have wilfully caused an issue with your changes. But I'd ask them - you've met me, what do I know

[Grant3]

This will affect your warranty, best speak to your local friendly dealer and see how sympathetic they are, I had a sports exhaust system with racing cats on a previous Porsche, still under warranty, and my local OPC was ok with this, but many aren't!

Your original question was about replacing the 2x 3-way cats with free flow items, but if you are also going for headers and exhaust change, my advice would be to -
A/ ensure you listen to how loud it is in and outside before having the conversion (although I know Bamford do a switch which is good), the combined changes can make it VERY loud!
B/ ensure you keep all the original items for re-fitting come re-sale as you will likely need these if you are going to sell the car back to the official network.
C/ See if (like Prodrive on their 4.3 kit)Bamford warrant any damage that "may" (unlikely I know!) occur due to the changes.

[DAMIT]

Got to ask why does AM fit six cats??

If taking them out and replacing with just two gives so much more power and weight saving, but still meet UK MOT emission limits. Why wouldn't you fit two to start with. It can't cost more can it?

Edited by DAMIT on Monday 9th April 14:48

[yeti]

DAMIT said:

Got to ask why does AM fit six cats??

If taking them out and replacing with just two gives so much more power and weight saving, but still meet UK MOT emission limits. Why wouldn't you fit two to start with. It can't cost more can it?

Passing emissions here, i.e. getting through the MOT is not the same as complying with emissions legal nonsense which also vaires from contry to country. What can be sold as a new car is not the same as what can be done to get through the MOT

Also type approval, endless testing for longevity, noise restrictions and cost!

[mikey k]

Not to mention the amount of unburnt fuel they kick out

[EBruce]

yeti said:

Changing out the last 2 cats is what I did originally with DMS, simply because it's easy and can be done while you wait. Remove old, replace with new. BR's system is far more intricate and has taken them a lot of work to delete all 6 heavy and restrictive cats and replace with 2 x 200cpi units, huge weight saving of course as well as power/torque gains.

Gains just for 2 x cat replacement... hard to say. I had, all at the same time, 2 cats replaced (10bhp?), QS backbox (7bhp?), J1 air filters (5bhp?) and ignition timing changed for super unleaded (8bhp?) so hard to say what they did on their own. However, the difference in driving and throttle response was amazing, but as to actual power...probably nothing hugely significant on their own. I think BR Mike's estimate was probably close to 25-30bhp all in on my car, hence my 'guestimate' bhp figures.

If you do your manifolds and cats with the BR system, you'll get 40bhp and a slab of torque due to the cat deletion, though with it being an 'S', you may already have the upgraded induction?

Warranty... well if an electric window fails, they aren't going to argue! Why would an exhaust cause a gearbox or engine issue either? Talk to your apparently friendly dealer and sound them out. I'm sure the official line is no changes, but realsitically, changing the exhaust can't cause the aircon to pack up, I would imagine they have to legally honour the warranty unless they can show you have wilfully caused an issue with your changes. But I'd ask them - you've met me, what do I know

Not hard to say when you do pre and post cat dynos. Saw a max of 18BHP at the wheels. Most impressive though was the Tq.

[yeti]

EBruce said:

Not hard to say when you do pre and post cat dynos. Saw a max of 18BHP at the wheels. Most impressive though was the Tq.

Was that just cats, no backbox or filters? Very impressive if so! I assume V8 rather than V12?

[MadMacMcMad]

Yeti, Are you on the TL site at LeMans?
If so, Bamford Rose will be there anyway. I think lots of loud Astons. Can't wait.

[yeti]

MadMacMcMad said:

Yeti, Are you on the TL site at LeMans?
If so, Bamford Rose will be there anyway. I think lots of loud Astons. Can't wait.

Yep, booked in with TL via them! Myself and Pommehogster in convoy, plus Mike and Bruce on their bikes. Arriving en masse Thursday mid-morning/early afternoon.