Cat-back Milltek or Decat back?

[Mk5 GTian]

I'm going for  this with JKM

http://www.jkm.org.uk/performance/tfsik03stage101.htm

including a cat-back Milltek exhaust,

But on Revo's website it says you need a decat-back exhaust when you go to Stage 2.

How does this work? do they change something in the cat-back exhaust? 

[da_ansa]

the original cat will still be on the car with that package, you would need to purchase a decat downpipe to go stage 2

[Nodz]

Basically there is 2 types of exhausts (as you probably know). Theres the cat back exhaust that goes from the pipe with the cat on or theres a turbo back exhaust that goes from the turbo and replaces the pipe the cat is on with either with a 200cel cat, 100cel cat or de-cat.

So to go stage 2 all you would need to do is replace that section of the exhaust (i think I've got that right). I'm sure not everyone has a decat for stage 2 tho

[bacillus]

For stage 2 you'll need either a down pipe with a sports cat or a decat. The latter won't pass the MOT emissions testing.

[Mk5 GTian]

For stage 2 you'll need either a down pipe with a sports cat or a decat. The latter won't pass the MOT emissions testing.

So I'd need to buy a new sports catalytic converter to pass the MOT at Stage 2? Can't I just swap the decat downpipe for the old pipe with cat in it for the MOT, and then swap them over afterwards? Or is that a bit naughty?   

[Nodz]

It is a bit but loads of people do it

[RedRobin]

^^^^
Yes you would have to swop to and fro to pass MOT if you want a decat. But don't forget to tell your insurer!

You don't have to have a decat to run Revo Stage 2. I run a Milltek turbo-back and have done so since 2005 from standard through Revo Stages 1 to 2.

[Mk5 GTian]

So I could in theory take the package detailed above, with a cat back exhaust, and run Stage 2 with no extra mods other than a high pressure fuel pump? Or is that wrong? 

[da_ansa]

So I could in theory take the package detailed above, with a cat back exhaust, and run Stage 2 with no extra mods other than a high pressure fuel pump? Or is that wrong? 

you would need either a decat or sports cat as it would be still running your original cat with that package

[bacillus]

Uprated hpfp is really only specified and needed for stage 2+...

[RedRobin]

Uprated hpfp is really only specified and needed for stage 2+...

....True but with a very efficient aftermarket air intake the standard OEM pump can hesitate or even cut out when under high demand. With a Forge Twintake, Milltek TBE, and Revo Stage 2, we (JKM) had to reduce the Boost setting a notch until an APR pump was fitted.

[Mk5 GTian]

Still quite confused  (Generally a bit slow on the uptake)

What is the difference between a Turbo Back exhaust and a Cat Back exhaust?

Am I right in saying that if I go for this package with a Cat back exhaust, when I go to Stage 2 I will need a decat downpipe or a sportscat downpipe, with the former meaning an MOT failure?

If I have a turbo Back exhaust, do I need a decat downpipe for Stage 2?

Has anyone got a diagram of both options? 

[Nodz]

A turbo back exhaust will include either a sport cat or de-cat

[RedRobin]

If I have a turbo Back exhaust, do I need a decat downpipe for Stage 2?

....No, with a Turbo Back Exhaust (often abbreviated to 'TBE') you don't need a decat for Stage 2.

A TBE is the whole system without keeping the OEM downpipe. In other words, A Cat-Back piping runs back from the Cat, and a Turbo-Back piping runs back from the Turbo.

Personally, I think that unless you've got a workshop etc and are used to doing car mechanics, the hassle for Cat swopping for MOT simply isn't worth it. Especially as exhausts aren't always the easiest to remove and fit after zillions of hot and cold cycles. Also, if you fit it yourself how does this effect your warranty?

[Mk5 GTian]

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Thanks Robin, I get it now. I think. 

So if I know I'm deffinately going to go to stage 2, I'd be better off getting a TBE with a built in sports cat, so I'll pass the MOT?