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De cat and down pipe

8.3K views 26 replies 12 participants last post by  mja.mercedes1  
#1 ·
Hey guys and gals, my catalytic converters have failed and so I’m looking at fitting a decat. There’s plenty of options, but I was wondering if anyone had ever used one of these Milan decats? They get good reviews on eBay but would be nice to know if anyone had used them on here and if so do they fit properly as I’ve heard some that are on eBay can knock against the power steering pipes and or the bulk head. Any help much appreciated. Thanks
 
#4 ·
What car have you got?

A 225 has plenty of 3in downpipe and sports cats... I have just refitted my pipewerx 100 cel sports cat, for if / when I finish the battery relocation etc... slowly slowly catch the monkey.

I had a decat on for post MOT and return the sports cat as required. The issue I had with my ebay cheap downpipe and sports cat was it needs to get proper hot to pass and gets more difficult each year. I'm hoping the pipewerx SC will pass easier as the DP and sports cat is 300 quid more from pipewerx, it went straight through the MOT last time.

You need an uprated dog bone mount bush otherwise the engine rocks and the flexi section of the downpipe will hit the prop shaft.

You'll not get any worthwhile extra power from a decat over a sports cat, unless you have a hybrid or something.. a stock K04 will only get about 280bhp \ 300ft/lb with or without a decat v sports cat

I had problems with fitment in the TT for both eBay downpipe and also pipewerx downpipe, but that was related to the Chinafold manifold.
 
#5 ·
What car have you got?

A 225 has plenty of 3in downpipe and sports cats... I have just refitted my pipewerx 100 cel sports cat, for if / when I finish the battery relocation etc... slowly slowly catch the monkey.

I had a decat on for post MOT and return the sports cat as required. The issue I had with my ebay cheap downpipe and sports cat was it needs to get proper hot to pass and gets more difficult each year. I'm hoping the pipewerx SC will pass easier as the DP and sports cat is 300 quid more from pipewerx, it went straight through the MOT last time.

You need an uprated dog bone mount bush otherwise the engine rocks and the flexi section of the downpipe will hit the prop shaft.

You'll not get any worthwhile extra power from a decat over a sports cat, unless you have a hybrid or something.. a stock K04 will only get about 280bhp \ 300ft/lb with or without a decat v sports cat

I had problems with fitment in the TT for both eBay downpipe and also pipewerx downpipe, but that was related to the Chinafold manifold.
I have a 2002 Audi TT 1.8T 225 (BAM). I know that they are are an mot failure. But I’m thinking of taking it off the road for a while and just use on the track. So that’s not an issue, I’m more trying to find out if anyone has previously bought and fitted a Milan down pipe and decat.

On eBay there are a few good reviews for this Milan decat and that’s why I’m asking as I know that the other Chinese down pipes/decats that are on eBay are a complete nightmare to fit.

If it comes to it and I don’t get anyone’s personal feedback from their own experience then I’ll just folk out the extra cash for a pipewerx kit as according to parrotbros on their YouTube channel they are the best on the market and have no problems when come to fitting.

And that brings me to my next question……. Do I match that with the most popular choice of cat back exhaust systems from either Milltek or Scorpion. Or do I go for a full custom made power flow system?? Has anyone else had their exhaust system done by power flow?
 
#8 ·
I was planning to get the Malian decat also but I’ve decided to get the Gravity one as it’s 10 quid extra and it’s a company that I have bought from ie FMIC
And they work a charm no problem
However for malian I do advice you that you will need better gaskets as the ones they supply you with are cardboard wrapped in foil
 
#10 ·
...as I know that the other Chinese down pipes/decats that are on eBay are a complete nightmare to fit...
I just bought a cheap ebay downpipe and sports cat... along with an expensive pipewerx downpipe and sports cat (and decat) they both fitted the same) as I said in my initial post the manifold has more impact. I expect most of these Chinese resellers just pick different quality things from the same places..

I will see if i can find the cheap ebay one I got
 
#11 ·
Thanks for all your help and replies! I’ve going to opt for a gravity decat/down pipe along with there Y cat back exhaust system. My next question is though, does my 2002 BAM have a KO3 or 4 turbo? It’s completely standard but been told that the gravity down pipe is only for the KO3’s? Thanks
 
#18 ·
Again thank you all for your help. I’ve bought a gravity decat and Y style exhaust system and just to be sure that I don’t get any knocking from the movement of the engine I also bought a Powerflex “black” dogbone mount. Oh and a green tip 😜 Next on the list is a Ramair induction kit and diverter valve 😁
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#19 ·
Isn't the black bush the diesel one? Or are they red?

Also did you get an oversized TIP?


Are you fitting them yourself? The 3 inch downpipe's decat pipe tappers down to 2.75inch to fit a stock catback, and I expect your new catback exhaust is 3inch maybe with s reducer to 2.75 to fit a stock cat pipe.... so be cautious before cutting anything as ideally you want to cut off the 2.75inch section from the decat, and not use the cat back reducer... but buy a 3inch ID sleeve...
 
#20 ·
Isn't the black bush the diesel one? Or are they red?

Also did you get an oversized TIP?


Are you fitting them yourself? The 3 inch downpipe's decat pipe tappers down to 2.75inch to fit a stock catback, and I expect your new catback exhaust is 3inch maybe with s reducer to 2.75 to fit a stock cat pipe.... so be cautious before cutting anything as ideally you want to cut off the 2.75inch section from the decat, and not use the cat back reducer... but buy a 3inch ID sleeve...
I had to buy a 3” exhaust sleeve as both pipes from the decat to the centre section are both 3”, found a stainless steel sleeve for £10 on eBay 😉

No black series powerflex are recommended for race use only due to them being so firm, but being as I’m only replacing the one bush to reduce the engine rocking I thought it would be the best choice rather than the softer purple series. The red series is for diesels.

And finally yes, oversized tip 😎 Once I’ve got the exhaust fitted I’m gonna get the tip, induction kit and DV on, then get a performance intercooler fitted ready for the final engine mod which is a dyno run remap.

Im also considering running it on a dyno after each mod fitted, I think it would be really interesting to see what extra power each mod gives me?
 
#24 · (Edited)
Yeah.. I thought the yellow were the normal big bush for the dog bone, they are quite vibratey for a few weeks I'm sure the black one will soften a little bit too... i've had my yellow powerflex bush for about 5 or 6 years now..

But you already have that green TIP is that oversized?

When are you fitting the downpipe? You'll probably need alignment afterwards, so if there any other related items, maybe get them done too? Track rod ends, lower arm ball joints etc?
 
#25 ·
Yeah.. I thought the yellow were the normal big bush for the dog bone, they are quite vibratey for a few weeks I'm sure the black one will soften a little bit too... i've had my yellow powerflex bush for about 5 or 6 years now..

But you already have that green TIP is that oversized?

When are you fitting the downpipe? You'll probably need alignment afterwards, so if there any other related items, maybe get them done too? Track rod ends, lower arm ball joints etc?
Yea the green tip is oversized, I wasn’t originally going to replace the tip but cos I’m fitting an induction kit and along with everything else I thought may as well change that too. The down pipe is being fitted in about 2 weeks. I didn’t know about the alignment having to be done after. So thanks for that. And as you say I may as well replace old for new whilst it’s all being done. What other parts do you think will be worth replacing at the same time? Thanks