V12 primary cat delete opinions

[AdamV12V]

ds666 said:

Don't think there is any chopping and welding to replace the secondary cats - think they are just bolted in ??
.

Yes, the secondaries are just unbolted and bolted in, just less than an hours work all in all.

It is the primaries that are chopped out and then welded back in - or in the cheapest alternative, just the ceramic catalyst material is smashed out and the empty canisters left in place. In one of BR's vids however they said this can cause a whoosing sound at certain revs. The full new manifolds is more like 11hours labour per side to replace, hence a rather expensive job.

Edited by AdamV12V on Tuesday 6th July 13:40

[anonymous-user]

dg73 said:

I have a 2017 Rapide S, currently stock. Think it produces about 550bhp as standard.
Car is currently at Bamford Rose for some other work.
Mike has suggested a primary cat delete with high flow secondary cat and ECU remap which I think will take it up to about 600bhp.

Have never felt the car lacks power or sound and not sure how much I'd notice an extra 50bhp on a 2 tonne car but I am open minded to anything that would noticeably enhance the drive.

If any V12 owners out there have had this done I'd be very interested to hear how you percieve it changed the power delivery experience or the sound!

Many thanks

I’ve had the BR primary delete plus high flow secondaries plus ECU flash.

The exhaust note is slightly different and the car feels a wee bit more willing through the mid range. It’s inevitably going to be marginal - it’s maybe a 5% hp gain.

You need the ECU flashed to suppress an engine warning light, I assume because the primaries aren’t there. I waited until I decided to end my Timeless warranty, which I did when I was told a faulty exhaust flap wasn’t covered (exhausts = consumables apparently).

It’s not easily reversible but I’d imagine that like most things it could be done with the application of enough money.

The primary cat delete is as you say externally not visible and the car will pass an MOT with just the secondaries in place.

At least one owner has had the secondaries removed by an AM dealer and then been told by the same dealer that they have to be swapped back in to pass the MOT. Reading between the lines, it’s the law that if cats have been deleted then it’s a MOT fail even if the car passes emissions, and the dealer is worried that as they know the secondaries aren’t there they can’t sign off on an MOT. But that car should sail through at any other MOT station.

The choice between primaries and secondaries depends in my view on your concern about primary cat ingestion and willingness to mess around with the car. For me the first was low but sufficient and the second was high enough. Everyone is different though.

[SHIFTY]

Most AM dealers (3 I know of) use the local MOT station to MOT the cars.

I would not have thought that the local MOT station would refuse to issue a certificate if the emissions all passed and most would not know the difference re original and non standard primary manifolds.

Have a look at

https://www.youtube.com/watch?v=Tf3lZz8z6TE at 1.07mins

[AdamV12V]

SHIFTY said:

Have a look at

https://www.youtube.com/watch?v=Tf3lZz8z6TE at 1.07mins

Yeah I have seen that before. He sure has a very annoying way of presenting information and I find his sarcastic tone somewhat offputting. Im sure I cant be the only one.

Anyway not really sure of what point hes making - is he trying to say that the emphasis is on the word "obvious" in that a primary cat delete isn't visiblby different to the eye of an inspector and therefore not "obvious"? I think the point the "jobsworth" he mentions or indeed the AM main dealers who wont pass a car with a such a mod is that it is "obvious" to them that it has been modified because they were paid to do the modification themselves earlier, so to plead ignorace saying its not "obvious" wouldn't likely stand up to any real scruitiny.

Anyway, most AM dealers wont fail a car they have modifiied just as BR wont, so other than one or two dealers being sticklers for the law I think in either primary or secondary delete's you'll be fine from an MOT pass perspective.

A Timeless warranty, which is a 3rd party insurance policy, is an entirely different matter however.

[Dewi 2]

BlackWidow13 said:

The primary cat delete is as you say externally not visible and the car will pass an MOT with just the secondaries in place.

At least one owner has had the secondaries removed by an AM dealer and then been told by the same dealer that they have to be swapped back in to pass the MOT. Reading between the lines, it’s the law that if cats have been deleted then it’s a MOT fail even if the car passes emissions, and the dealer is worried that as they know the secondaries aren’t there they can’t sign off on an MOT. But that car should sail through at any other MOT station.

Perhaps the AM dealer was just being extra careful, knowing that they had altered the exhaust, in case the customer was a 'mystery MoT shopper'.

I think theoretically, an MoT tester is supposed to carry out a visual check, to see whether the exhaust system has a non-original appearance, but as already mentioned, the testers won't know every vehicle. The BR mod to V12 primaries, presumably leaves the original appearance unaltered, whereas a replacement manifold without cats to heat quickly, perhaps should technically fail the MoT visual test.

I recently noticed advisories on someones MoT, 'undertrays are concealing parts of the exhaust system'.
Thought MoT advisories are usually about something requiring attention.

[dg73]

Thanks to everyone for their input. Given I’m not bothered about making the car louder and the power increase is only circa 5% I’m not sure it’s worth all the potential hassle with the warranty and the cost of doing this mod for the time being.

Given all the minor but irritating issues I’ve had with the car and resultant heavy usage of the warranty I’m reluctant to jeopardise renewal…

[dbs2000]

ds666 said:

Don't think there is any chopping and welding to replace the secondary cats - think they are just bolted in ??

Correct

ds666 said:

I was considering the primary replacements ( full system ) but I'm told the exhaust sound is significantly different to the standard system ( more Ferrari like ) - one chap I know of says it is the worst thing he's done to his DBS . I like the current sound.

.

Also correct. I had the full system:
https://www.youtube.com/watch?v=2xV6E3ka298

and missed the lovely burble so I went back to a standard manifold minus the primaries and high flow cats. The sounds was perfect.
https://www.youtube.com/watch?v=MaU0Q0bn4Ls. (sorry its not a long clip)

[magycks]

dbs2000 said:

Also correct. I had the full system:
https://www.youtube.com/watch?v=2xV6E3ka298

and missed the lovely burble so I went back to a standard manifold minus the primaries and high flow cats. The sounds was perfect.
https://www.youtube.com/watch?v=MaU0Q0bn4Ls. (sorry its not a long clip)

are you able to re-share the first link? says it's a private video . 2nd still works.

[dbs2000]

I had no idea that was on, changed now.