Is anyone running a fully de-cat standard exhaust ?

[Bladerider]

If its any help,

I have a pair of decat downpipes I bought as a trial that Im about to list.

I bought them in good faith as fitting a Milltek cat back but they are not going to work with my Milltek non res centres as they are not long enough, so I have been forced to get new dowpipes, but they are perfect for someone wanting to keep their original cats for when its MOT time or as a trial to work with a stock exhaust as you can cut the existing exhaust in just the right place, in fact i think they may even have a join where the standard crossover join is, I only looked at em in place with the Millteks for about 30 seconds when i saw the car the other day.

Pm me for details if you wish.

J.

[TAB1S]

This is a route i wanna go down but was wondering how big a gain it is to go for after market cat back milly etc over just removing the cats completely?
Cant help but think they are massively overpriced for what they do and the cats are the main restriction.
MOT's are not a concern regarding decat for me.
Thanks

[NJMAudiRS4]

I had a full decat system without valves and it wasn't bad, but it did drone on long journeys, it did fail the MOT as the law changed on the 1st March this year and if your car was produced with cats then they must be visible at mot time.
I had a custom system made from JC Weldfab with sports cats cheaper and much better quality and sound than Miltek
It seems that the best option is to remove the precats completely and then turn the cats 180* no need to space out the lambda sensor no error codes shown.
Regarding any power gains just removing the pre cats seem to give good figures, the standard cats are regarded as being quite good, I believe 400 cel, so not overly restrictive obviously sports cats would be better. Many comments have been made regarding actual power gains from Miltek systems with the majority saying it's just about the noise and doesn't increase the bhp. IMO and after reading through this forum that to get any increase in bhp you would need the following
A decent exhaust system manifold back with sports cats, a full carbon clean (MRC) and a custom map (MRC) job done

Nick

[Rick_RS4]

I run a full non res valved, cat bypass Milltek system. Valves closed quieter than with cats, S button valves open = gods thunder, screams its bolx off at 8k revs in 3rd.
Absolutely 100% love it and recommend it. More HP and Torque see the following thread:

https://www.facebook.com/media/set/?set ... 49.1548228

thats great figures, did mrc say you could squeeze any more out ? with say stage 2 manifold etc?

[MikeFish]

Regarding any power gains just removing the pre cats seem to give good figures, the standard cats are regarded as being quite good, I believe 400 cel, so not overly restrictive obviously sports cats would be better.

The pre cats are 400 cell but the OEM cats are only 200 cell. Most sports cats are either 200 or 100 cell so not much to gain by fitting a 200 cell sport cat other than it saves you have to gut the pre cats but obviously gutting the pre cats will give you similar gains as fitting a 200 cell sports cat.

[dickytrickster]

I've just gutted my spare down pipes ready to go on next week. Does anyone have any sizes for the spacers need to not throw the cel?

[Covkiller]

thats great figures, did mrc say you could squeeze any more out ? with say stage 2 manifold etc?

My car is standard post MRC Carbon clean, ie, flaps in place as opposed to a stage 2 manifold and no cold air feed. Doug says it's one of the best power outputs even compared to Stage 2. There's no more power to squeeze out. It's now on 447PS and 477NM, I love it and I'm going to absolutely thrash the bolx off it when I go to the ring in June then Berlin re work after.
I cant bloody wait !

[NJMAudiRS4]

Regarding any power gains just removing the pre cats seem to give good figures, the standard cats are regarded as being quite good, I believe 400 cel, so not overly restrictive obviously sports cats would be better.

The pre cats are 400 cell but the OEM cats are only 200 cell. Most sports cats are either 200 or 100 cell so not much to gain by fitting a 200 cell sport cat other than it saves you have to gut the pre cats but obviously gutting the pre cats will give you similar gains as fitting a 200 cell sports cat.

My apologies, for the misinformation I thought the main cats were 400 cell not 200 cell, thanks Mike for correcting this.

[MikeFish]

Regarding any power gains just removing the pre cats seem to give good figures, the standard cats are regarded as being quite good, I believe 400 cel, so not overly restrictive obviously sports cats would be better.

The pre cats are 400 cell but the OEM cats are only 200 cell. Most sports cats are either 200 or 100 cell so not much to gain by fitting a 200 cell sport cat other than it saves you have to gut the pre cats but obviously gutting the pre cats will give you similar gains as fitting a 200 cell sports cat.

My apologies, for the misinformation I thought the main cats were 400 cell not 200 cell, thanks Mike for correcting this.

No worries