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My car is going to MRC in a couple of weeks as it needs a decoke after 80k and this has caused the inlet flaps to both stick.
Whilst there, I'm having it de-flapped and the stage 2 map tweaked to allow for the work they do.
My question is, whilst it's there is it worth gutting the pre cats? Is there much to be gained? Power? Sound?
I'm running a non res valved Milly also.
Thanks..

Yes, the precats are one of the biggest loses on the standard car. Precats are 400 cell, main cats are 200 cell (Milltek sport cats are available as either 100 or 200 cell so the OEM main cats are same as one of millteks sport options).
There is slightly more noise I'm told too (I had a lot of other work done too at the same time inlcuding a Tuni exhaust so can;t comment on how much noise difference it made).
Warning, you will most likely get a little smoke when first starting the car or for the first couple of minutes when cold.

Thanks Mike, I'm just trying to get though to MRC but they're not the best for answering the phone.
Need to wiegh up the cost of it and is there sufficient gains.

MRC are asking £450 for this job. 5 hours they say.

Starry wrote:MRC are asking £450 for this job. 5 hours they say.

Cheaper than a carbon clean and the effects are permanent! (unlike a carbon clean)

MikeFish wrote:

Starry wrote:MRC are asking £450 for this job. 5 hours they say.

Cheaper than a carbon clean and the effects are permanent! (unlike a carbon clean)

Maybe, but with both my inlet flaps fooked and In turn making my dash light up like Christmas tree it is an necessity.
It's running in limp mode and limiting the revs at the moment.

I'd look into getting a local custom exhaust Shop make you up some new downpipes, retaining the main 200 cell cats (ditching the pre-cats).

It should cost you the same, but then you end up with a cleaner exhaust flow rather than having some empty hollowed out swirl boxes in the downpipes.

FaisalJ wrote:I'd look into getting a local custom exhaust shop make you up some new downpipes, retaining the main 200 cell cats (ditching the pre-cats).

It should cost you the same, but then you end up with a cleaner exhaust flow rather than having some empty hollowed out swirl boxes in the downpipes.

I think most of the cost is in removal due to snapping studs. Smashing the cat out would be easy once off. As for cleaner air flow without the cat casing, your probably right but I wouldn't of thought it would make much difference. But who knows?

Starry wrote:Maybe, but with both my inlet flaps fooked and In turn making my dash light up like Christmas tree it is an necessity.
It's running in limp mode and limiting the revs at the moment.

Just a thought, and assuming that the revs are limited at 7000rpm......

- Do you get the kick at 5500rpm from the vacuum operated 'power flap' in the air filter?
- Do the flaps on both banks report the fault code?
- Didn't the car have a detail just before you bought it?

If yes to all those, then it's very probable that you have a vacuum system leak (maybe a pipe got knocked during the detail?), since the manifold flaps and the power flap are all vacuum operated.

Just my £0.02 which may help

chirs4 wrote:

Starry wrote:Maybe, but with both my inlet flaps fooked and In turn making my dash light up like Christmas tree it is an necessity.
It's running in limp mode and limiting the revs at the moment.

Just a thought, and assuming that the revs are limited at 7000rpm......

- Do you get the kick at 5500rpm from the vacuum operated 'power flap' in the air filter?
- Do the flaps on both banks report the fault code?
- Didn't the car have a detail just before you bought it?

If yes to all those, then it's very probable that you have a vacuum system leak (maybe a pipe got knocked during the detail?), since the manifold flaps and the power flap are all vacuum operated.

Just my £0.02 which may help

£0.02 are always welcome the car hits the limiter at just over 7k and is showing faults on both sides.
Don't notice any increase in anything at 5.5k but I've only ever driven one b7 and only for about 300 miles in total.
The car feels flat to me, seems to pull well low down but to so much as the revs rise.
The car has recently had a detail though..

Starry wrote:the car hits the limiter at just over 7k and is showing faults on both sides.
Don't notice any increase in anything at 5.5k...
The car has recently had a detail though..

Definitely get the vacuum system underbonnet checked out then.
Sounds like you could have a vacuum leak, maybe a pipe got dislodged when it was detailed?

Well hopfully MRC will find a leak if there one. I've just bought the car so I think a cc, de-flap and pre cat removal with the stage2 map tweek will give me a good platform to go forward with.
P.s I drive to work this morning and payed attention to the 5.5k mark and there's definitely no change/surge