AM DB9 Secondary & Primary Cats

[Li-yjlki]

Hi all,

First post so be gentle - became proud owner some months ago of a 07 DB9 manual with sports pack and thoroughly enjoying it.

And yes - for all the people considering - i do have a baby seat in the back seats for my 2yr old.

I have a few motorbikes of which all are heavily modified and the DB9 is too quiet for my liking - I did look at the different topics and don't want any droning so am considering the secondary cat removal and potentially primary too for preventive measures whilst keeping the backbox stock (unless a dbs pops up somewhere).

However, there seems to be a multitude of different secondary cat removal options on the evilbay etc - does it really matter which one to go for? and then go to somewhere for the primary removal and ecu update etc?

Thanks in advance

[GG33]

Secondary cat removal is easy, just swap out the cats for by-pass pipes, they are not cheap at about £500 for a pair. Primary cat removal is a different ball game as they are built into the exhaust headers. You would need to remove the headers and break out the cats (not a quick or simple job) Bamford Rose will sell you a new set of performance headers without cats, but they're not cheap either....

GG33

[Green9]

Hi - congrats on the car. I have a DB9 manual Volante which I love. Just checking you’ve removed fuse 22 which leaves the exhaust valve open. It may still be too quiet for your tastes but I have to say it’s noisy enough for me, no droning etc and I do love some noise...

Which car seat did you fit in the back? I also have a 2 year old...

[EVR]

Congrats.

As previous gentlemen suggested, I would first try the fuse route (super easy and zero cost). Then, the secondary decat one, by visiting a local exhaust fabricator, they will be able to fabricate two delete pipes (they are very easy and simple, both to do and install).

If still not happy, I will take a look at your more expensive options for the primary cats. Of course, I am talking from a V8 perspective, I do not have to deal with the potential cat ingesting problem of the V12, so keep that in mind.

[Li-yjlki]

Thank you all.

I actually did try the fuse22 but when accelerating wasnt very loud - my bikes have full systems no cats so quite a big difference and do prefer a quieter mode in the mornings etc so hence looking at the secondary cats etc.

Again, a bit of a weird one because apparently there are no cat/ ie decat or performance cat options? why go performance cat when a decat is better? I dont think i've heard of performance cat from the bike world so apologies if this is basic stuff

I would have thought decatting the primary would be more labour taking off rather than the actual fabrication cost but happy to hear if anyone has gone down that route. Or can this be completely mitigated if just ontop of coil and spark plug changes?

Thanks!

[andy_ran]

Keeping on top of plugs and coils is critical on these. The valve overlap means a misfire can kill the cat and then get sucked in destroying the engine

Hence the removal of the primary and replacement of the secondary with sport cats - According to trusted sources I have watched and read from,the earlier cars where more problematic than later ones?

I have done a secondary cat removal on my V12V and it made a vast difference to the noise, as it should have come from the factory IMO

[8Tech]

I have seen V12 manifolds that have simply had the cats removed and then refitted but considering the work to remove them, I would rather install tuned equal length manifolds without cats. You will need relocated O2 sensors and secondary cats to prevent engine management fault lights.

[Aldhun]

8Tech said:

I have seen V12 manifolds that have simply had the cats removed and then refitted but considering the work to remove them, I would rather install tuned equal length manifolds without cats. You will need relocated O2 sensors and secondary cats to prevent engine management fault lights.

What sort of cost would that incurr?

[paulrog1]

If the primary cats are removed you will need to re-program the car so that the emissions light doesn't come on, so not an easy home DIY job.

Garages like BR do this kind of work regularly, i'm gunna take mine there soon.

Secondary cats are an easy DIY job.

[Dubsands]

On all V12 this is a nice video by Mike at BamfordRose on Primary Cat delete options, particularly the option of retaining the original exhaust manifold and simply removing the internal ceramic material. Scrub through to time point 1-35 to get a good idea. You would still need to re-map the ECU.

https://www.youtube.com/watch?v=mcBtHj60BJ8