Milltek cats & downpipes.....again!

[KayGee]

Stock to Stage 2. Full exhaust plus remap.

[DavidT]

You guys really spend too much money on tuning in Europe.

I've not spent anything in this area yet

Did you get my email Verruckt?

[S2tuner]

Totally agreed with Chris on this one, gutting the pre-cats works almost as good as doing expensive downpipes, and removing the cats is always an option too, but on 2000+ cars the ECU needs to be programmed so it accepts the no cat condition with no fault codes.

HTH,

[Dippy]

You guys really spend too much money on tuning in Europe.

Remove the "on tuning" and your sentence is correct. Prices in Europe (and particularly the UK) have always been much higher for the same thing than in the US.

Exactly what is included in each tuning stage varies by supplier, however I think for a B5 S4 it should be roughly:

Stage I: Remap only (may include cat-back but the difference is negligible)

Stage II: Modifications to the 'breathing' i.e. free-flow cats, and corresponding remap (of course should include cat-back too).

Stage III: Uprated turbos, air intake and fuel injection.

Stage IV: Engine work (heads, cams, manifolds etc).

Typical prices for stage I are £500 to £1500 depending on which tuner and if you have a cat-back.

For stage II you are looking at another £1000 to £1500.

My advice is that if you have a stage I and then go back to the same tuner for stage II then your remap should be free.

Moktoya, you asked for advice on getting a new map. I suggest you take your car for some test runs and consider very carefully:
1) Do you feel ANY loss of acceleration up to the redline (remember how the stage I felt?)
2) Does the oil temp really rise a lot after driving around using a lot of high revs?
If the answer to either is yes, then your map is not taking full advantage of the exhaust system. You REALLY should have flat acceleration to the redline. Also part of the reason for adding fuel at the top end is for cooling - if the turbos get too hot it affects their efficiency. I'm sure that our resident gurus can expand on that...

[Verruckt]

You guys really spend too much money on tuning in Europe.

I've not spent anything in this area yet

Did you get my email Verruckt?

Yes I did and I apologize for not replying yet. I just got back to Europe and have a lot of things to catch up on. Thanks.

[DavidT]

Yes I did and I apologize for not replying yet. I just got back to Europe and have a lot of things to catch up on. Thanks.

No worries. Let me know when you are ready

Apologies for hi-jacking the thread.

[Nige_RS4]

Totally agreed with Chris on this one, gutting the pre-cats works almost as good as doing expensive downpipes, and removing the cats is always an option too, but on 2000+ cars the ECU needs to be programmed so it accepts the no cat condition with no fault codes.

HTH,

Mihnea / Veruckt,

Are there any DIY guides for gutting the pre-cats? Looked on AW and can only find basic stuff? Is there anything to watch out for when doing it i.e. will the O2 sensors needs relocating?

Cheers, Nige.

[Mik]

Interesting re gutting the cats, however would that not cause higher emissions - i.e. potential failed MOT etc.?

Mik

[Verruckt]

Totally agreed with Chris on this one, gutting the pre-cats works almost as good as doing expensive downpipes, and removing the cats is always an option too, but on 2000+ cars the ECU needs to be programmed so it accepts the no cat condition with no fault codes.

HTH,

Mihnea / Veruckt,

Are there any DIY guides for gutting the pre-cats? Looked on AW and can only find basic stuff? Is there anything to watch out for when doing it i.e. will the O2 sensors needs relocating?

Cheers, Nige.

Yes, you will need to re-locate the secondary O2 sensor to just beyond the main catalyst otherwise you will cause a warmup catalyst efficiency code.

Otherwise, there isn't much of a procedure. Take the downpipe off and ream out the pre-cat material using a high speed drill of sorts and remove as much as you can. Here is a picture of the finished product.

Interesting re gutting the cats, however would that not cause higher emissions - i.e. potential failed MOT etc.?

Mik

No, you will be fine. Gutting the pre-cats (main cats intact) only effects emissions slightly on cold starting. Once the car is warm (when emission measurements are taken), it will be the same as any normal S4.

Aftermarket downpipes are basically the same thing with the pre/warmup catalysts removed. This is where most of the power gains from downpipes come from.

[S2tuner]

Mik, what do you think the problem would be then with Milltek downpipes that have no precats at all, and only metal main cats, that from a cat standpoint, are less efficient to do their job??? No, you won't fail MOT!!!

Interesting re gutting the cats, however would that not cause higher emissions - i.e. potential failed MOT etc.?

Mik

[Mik]

I take your point Mihnea.....just being careful I guess. I must admit I quite fancy doing this over spending 3k on a full Milltek system.

Mik

[DavidT]

At what point is a larger capacity exhaust system needed, if at all ?

[S2tuner]

A larger system is always better, and ANY engine does benefit from less backpressure in the exhaust, no matter what turbos you're running. I've just recently done an S4 with a complete RS4 engine, Milltek dual system with gutted precats and no cats. Well, honestly, I don't know of any other RS4 engine that breathes like that on 1.3Bar boost, the car is simply breath-taking. At 155mph, mash the loud pedal and you're doing 185 in a couple of seconds...

[Nige_RS4]

Yes, you will need to re-locate the secondary O2 sensor to just beyond the main catalyst otherwise you will cause a warmup catalyst efficiency code.

Is this difficult for a garage to do - I mean do you have to drill and tap a thread into the DP?

TIA.

[moktoya]

Dippy,

Acceleration in the top end much improved after installing the Milltek cats, but it just doesnt feel linear all the way to redline...tapers off after 5.5k as i said. Engine gets hot after runs at high revs which i would have thot is very normal. OK, here in Asia outside temp hovers at 30 celsius + in summer, but this time of yr it's mid teens to low 20's. Sustained high speed/engine speed runs during winter my oil temps rise to 110 (but drops very quickly since i also have an aftermkt oil cooler installed.) Do u get cooler temps with yours after hard runs?

Also, lastly, do u think i should pay to upgrade my MTM programme to the sport cat stage? OR shld it be free? Thx