Downpipe-Decat TDi advice

[daboy3000]

I know my way round a car but the exhaust system is something I don't know a lot about.  I have heard that replacing the downpipe will help my turbo spool faster and getting a decat pipe will increase throttle response.  Is the cat in the downpipe? if not what would I need to replace?

I don't want to spend lots of money but I would never put a budget part on my car, what do people recommend that's good value for money and what exactly do I need?

[dodds-gttdi]

The turbo is right behind the engine with the exhaust outlet facing toward the passenger side. The downpipe joins onto this with a vee-band clip (like a type of jubilee clip). There is only maybe 6 inches of downpipe before you get to the catalyst which can be best described as almost box shaped and not so great for free flow. The catalyst is small(ish) and sits pretty much next to the turbo. The exit pipe travels down from the bottom of the cat at a 45 degree angle towards the back of the car and levels out when it reaches the floor pan. You will have a middle silencer just in front of the passenger side wheel as well as the back box at the rear.

One of the best things you can do for improving flow thru your exhaust system is to remove the back bock and have straight pipes to the back of the car. See page three of my build thread for what I had done. From this you will hear your turbo spooling, you will also loose whatever weight is in the back box and you should notice it revs a bit easier.

The best (but slightly more expensive) set up you could use is to get a large bore downpipe (with decat) from the likes of Milltek or other exhaust company. If you go for a non resonated exhaust this will exclude the mid-silencer but this will give you a back box again (I presume you will need some sort of back pressure as eithout a catalyst, mid-silencer or rear silencer/backbox you would have a straight pipe out from the turbo back!!  )

HTH

Dodds

[daboy3000]

I have a GTi back box already fitted, don't really have the money to do the whole system.

So am I right in thinking all I need is a 2.5"/3" decat downpipe and some sort of size adapters?

Miltek the one to go for then?

Thanks for all the info Dodds, really helped.

[daboy3000]

This right and a good price?

http://www.fr-rtuning-shop.co.uk/index.php?_a=product&product_id=104

[Andy]

he is a pic of the front pipe connected to the turbo

[dodds-gttdi]

Yeah, thats a good price. I got my system second hand from a member on here but when I was looking a downpipe was anything from £170-£200.

The Milltek downpipe runs right up to just before where the middle silencer bends off to the passenger side. I took my old system off in one go and then fitted the Milltek so I don't know how how much distance/gap you will get between the milltek downpipe and the OEM middle silencer. Remeber to take plenty pictures if you do go for the downpipe. I'd be interested to see how it all works out. 

[daboy3000]

I have just had a chat with FR & R Tuning and they have recommend the THS one, he said its the same quality as the Miltek and comes with the adapters to fit the OEM centre section.  £145 inc VAT & delivered. Seems good.

[dodds-gttdi]

Lovely stuff. End of the day a down pipe is just a straight thru pipe, shaped to your car so there's not a lot that can vary between makes. I suppose materials used and weld quality. But for that price you're getting a bargain. If I were you I'd enquire into a THS mid-box delete pipe (if one exists). From the money you have saved not going milltek you would end up with a totally sorted exhaust for a very decent price. 

[daz_pd]

let us know how it goes with the THS, thinking of one of these for SWMBO's Leon!

[daboy3000]

Will the decat cause any lights to come on?  If so is it something my indy can do with VAGCOM or is it more specialised and therefore will need to be mapped out?

[dodds-gttdi]

For the TDI you won't get any warning lights etc as you don't unplug any sensors. Piece of cake to change over. :-)

[Andy]

As mentioned there is nothing to unplug to bring any lights on,

[vRSAlex]

I chucked a decat pipe on the misses's tdi 140 altea yesterday that I got off here.  Noticeable improvement. Revs and boosts smoother and seems to hold slightly higher boost at 4k.  Nice and easy to fit too.

It's not a ths pipe, but I would have got the ths version if this one hadn't come up cheap on here.

[daboy3000]

On a scale of 1-10 how easy are these things to fit yourself and what equipment would I need.  I would say that I'm a novice but have changed things like a ball joint on a mk1 and taken bits of engine apart to clean but only things like pipes and filters etc.

Just thought, I would need to put it on a ramp, that, I don't have!!.



Update: Ordered, can't wait!

[vRSAlex]

I fitted mine on a ramp which makes it much easier.

If you get the front end up on axle stands then it will still be fairly easy.  There is a bracket going from the dp to the gearbox.  Remove the two bolts using a 16mm socket.  The dp is held onto the exhaust with a clamp.  Just loosen the two nuts with a 13mm socket.  There is a bracket mounted to the body of the car that tends to get in the way so whip that off.  It's either got 17mm nuts or 13mm nuts.  The downpipe is attached to the turbo with a v-band style clamp.  Undo this with a 5mm allen key.  The clamp tends to stick to the exhaust and turbo but this can be released with a screwdriver or pry bar.  Last thing is to take off the two bolts that hold the mount to the back of the subframe with a 13mm socket again.  Fitting is the reverse.