Help needed about Cats and Exhausts

[ClaireTME]

Hi all well had some problems with my MK5 GTI it was due a service and a look as i think it was losing power, the VW garage did the service and said a sensor was broken so £100 for that but still a power loss, they have said to me they think the Complete exhaust needs replacing? Yes all of it? When i asked why they said the CAT when you shake it was making a noise as the flow was not correct thus losing power? they give me a quote of about £750 to replace the whole exhaust,  the question is how many cats do they have and do i need to replace the whole system? if so can i get a complete exhausts from the turbo with a sports cat or something, any help on this please..

[nr123]

It has only one 'CAT' lol. It's called a catalytic converter, it's very rare for this to go. It changes the gases coming from the engine into more safe chemicals. What year is the car? Is it a full VW history?

[Chris MKV]

You can fit a sports cat   but I think will need a full exhaust as they are generally wider bores. I think a system is around a grand jkm at Portsmouth list a few option on their www site.

The milltek seems the most popular of these.

I'm sure that someone will be along to tell you how good these are - my exhaust is stock I'm afraid.  :embarassed:

[ClaireTME]

It has only one 'CAT' lol. It's called a catalytic converter, it's very rare for this to go. It changes the gases coming from the engine into more safe chemicals. What year is the car? Is it a full VW history?

Hi yes this is why it hass peed me off its a 55 plate Full VW service and 30k mikes so not a lot. Also is it one system complete i can not understand why they would say replace the whole system if its onlt the cat gone why not just the section with the cat in??anyone

[Gene Hunt.]

Hi all well had some problems with my MK5 GTI it was due a service and a look as i think it was losing power, the VW garage did the service and said a sensor was broken so £100 for that but still a power loss, they have said to me they think the Complete exhaust needs replacing? Yes all of it? When i asked why they said the CAT when you shake it was making a noise as the flow was not correct thus losing power? they give me a quote of about £750 to replace the whole exhaust,  the question is how many cats do they have and do i need to replace the whole system? if so can i get a complete exhausts from the turbo with a sports cat or something, any help on this please..

........was it a main VW dealer or an independent ?. Either way i would be asking someone else.

[Ed30DSG]

There are 2 cats in the down pipe, a pre-cat and main cat - both are 400cell and are very restrictive.

You can just replace the downpipe with either a milltek sports downpipe (£500) or find a used OEM downpipe on ebay (from £20).

Having said that, I can't see a damaged cat causing your problem - it must be another sensor - there are 2 sensors in the downpipe, but it might be the MAF or another small part that has failed.

You need to take it to a specialist who know these cars better than the dealers - yuou don't say where you are based??

[Hurdy]

ED30 DSG is right about the pre-cat and cat.

An aftermarket system will cost you approx £1100 to £1350 new and fitted and that would be a full stainless system with a limited lifetime guarantee from the manufacturer.

The main three aftermarket exhausts are:- Milltek, Blueflame and APR.

Every now and again one will appear on the forum classifieds and to include the cat you will need a full turbo-back system and not just the "cat-back" system.

It is rare for the cats to go, but not unheard of. Main reasons are high EGT's (Exhaust gas temps), which arise from running too lean and is generally an issue with cars that have/are remapped and misfuelling the car. Both of these would burn out the centres of the cat causing blockage and even higher EGT's, which then makes for a viscious circle until it fails completely. At least if their diagnosis is wrong you will have a decent exhaust that you could keep or sell on.