There's been alot of talk on cat back systems recently, which has been great for seeing all the options and experiences. But now I'm thinking about a sports cat too! So was after a similar thread of options and advice from owners.

2.5" or 3"? What's the standard diameter anyway? Not planning on going BT at any time.

100cell, 200cell....? Again what's the standard cat? Looking to pass MOT's obviously.

Main options I see are:

Piper - 200cell - 2.5"

APR - ???cell - 2.5" or 3"

Milltek - ???cell - 3"

Blueflame - 200cell - ?"

Most of them seem to be around the £340-420 mark, apart from the rather pricey APR ones!

Cheers in advance guys

The standard one is less than 2"

From what I've read, 2.5" is plenty unless you're planning on big turbos. Standard exhaust system is 2.25" and most cat back systems seem to be 2.5"

I've gone for a 2.5" decat - but there are no emissions tests here.

i have a 3 inch pipe werx unit with 100cell sports cat and have no mot issues ever...

if you going to get one go for the larger bore allows the heat to disapate from the turbo better and the main cause of turbo failure is heat so its got to be a good thing:thumbup:

The standard one is less than 2"

From what I've read, 2.5" is plenty unless you're planning on big turbos. Standard exhaust system is 2.25" and most cat back systems seem to be 2.5"

I've gone for a 2.5" decat - but there are no emissions tests here.

Cheers for that Rob, didn't know the standard downpipe was so skinny! Don't suppose you could check the diameter of your old one after you whip it off. Just interested to know.

i have a 3 inch pipe werx unit with 100cell sports cat and have no mot issues ever...

if you going to get one go for the larger bore allows the heat to disapate from the turbo better and the main cause of turbo failure is heat so its got to be a good thing:thumbup:

Ahhar! Is it this one: Audi TT 180 Quattro 3" Exhaust High Flow Sports Cat on eBay (end time 03-Dec-09 11:21:31 GMT)

Would be good to know the turbine housing outlet ID for interests sake. Do you know if anyone has tested a 3" downpipe versus a 2.5" downpipe on the front of a 2.5" system?

I'll add PipeWerx to my list!

I've got a BF one and I'm very happy with it.

Your welcome to come have a spin next time your in the area mate.

When i worked at Piper and we did this development, we found that a 2.5" bore downpipe was the best option for the K03/K03s turbos. They can comfortably handle up to and beyond what the turbo is capable of flowing (260bhp). We found that going larger caused a great deal of turbulance in the downpipe and the flow was reduced up to around 4000rpm, and after that was only the same as the 2.75" and 3.0" versions we also tested.

With the cats, we decided upon a 200CPSI as the flow difference between 100 and 200 was neglegable. The 100 did flow better, but because it has less coated surface area they do not last as long. If you plan of keeping the car a while, i would advise a 200CPSI version. If you either do few miles, or do not plan on keeping the car too long then a 100CPSI will be fine.

I cannot say if either will cause a problem with the MIL light as my car was allready mapped for a sports cat when we did the testing.

I hope that gives you a little insight into the various options

Kind Regards

Garry

Top post Garry!

Mine is 100cel, touch wood it seems OK to me but given the option now I'd probably try the 200cel.

I've got a BF one and I'm very happy with it.

Your welcome to come have a spin next time your in the area mate.

Cheers for the offer mate. Your car must be pretty fruity after the Stage 2!

My plan is full turbo back exhaust, then custom map. Looks like just over £1000 for about 40bhp extra. Not bad I don't think!

Might be down your way over Christmas....

Give me a couple of days notice mate and you can see for yourself!

When i worked at Piper and we did this development, we found that a 2.5" bore downpipe was the best option for the K03/K03s turbos. They can comfortably handle up to and beyond what the turbo is capable of flowing (260bhp). We found that going larger caused a great deal of turbulance in the downpipe and the flow was reduced up to around 4000rpm, and after that was only the same as the 2.75" and 3.0" versions we also tested.

With the cats, we decided upon a 200CPSI as the flow difference between 100 and 200 was neglegable. The 100 did flow better, but because it has less coated surface area they do not last as long. If you plan of keeping the car a while, i would advise a 200CPSI version. If you either do few miles, or do not plan on keeping the car too long then a 100CPSI will be fine.

I cannot say if either will cause a problem with the MIL light as my car was allready mapped for a sports cat when we did the testing.

I hope that gives you a little insight into the various options

Kind Regards

Garry

That's what I'm talkin' 'bout! Excellent info there Garry. That's just what I wanted to know. Oh and thanks for the PM too!

Just spotted a picture of you enjoying a beer and a curry!! http://www.motorsportworld.co.uk/

Just found this data from the Jetex website too. Same as the Piper, with 200cpsi and 2.5" bore.

Rolling road results for new Jetex 1.8T large bore downpipe and sports cat!

lol, yeap, hard at work in Barcelona on a "Business" trip

well ive had in the past

Miltek 200cell 2.5inch less noise then blueflame, no cell light, noticeable imrpovent straight away, great fitment, just the rest of the cat back that was a rubbish fit, more expensive then blueflame, went through mot no prob

Blueflame 100cell 2.5inch was on a previous car so cant comment about the fitment, though removal was nice and easy and had no problems, no cell light again, and slightly noiser then the miltek, cheaper then most sport cat downpipes, and again loads of mots no prob

and decat 2.5inch, lots of noise, popping and banging, cell light on, improvement in mpg and pickup noticeable, cheap as chips on various sites, wont pass mot

Edited 6 November, 200916 yr by TrevorB33

Nice round up that

Didn't know your company existed Garry, looks like you do some top kit mate!

Cheers mate

Yeah, i think we have most of the big names covered

Kind Regards

Garry

1877967[/color]]When i worked at Piper and we did this development' date=' we found that a 2.5" bore downpipe was the best option for the K03/K03s turbos. They can comfortably handle up to and beyond what the turbo is capable of flowing (260bhp). We found that going larger caused a great deal of turbulance in the downpipe and the flow was reduced up to around 4000rpm, and after that was only the same as the 2.75" and 3.0" versions we also tested.

With the cats, we decided upon a 200CPSI as the flow difference between 100 and 200 was neglegable. The 100 did flow better, but because it has less coated surface area they do not last as long. If you plan of keeping the car a while, i would advise a 200CPSI version. If you either do few miles, or do not plan on keeping the car too long then a 100CPSI will be fine.

I cannot say if either will cause a problem with the MIL light as my car was allready mapped for a sports cat when we did the testing.

I hope that gives you a little insight into the various options

Kind Regards

Garry[/quote']

erm is that sposed to say that Garry? or am I readin it wrong?(I hope so)

back on track, I went in to get a DP made by Longlife seen as they made my cat back, they said that the std DP is made so the air flows properly and putting on a 2.5" one would mess it up? I already have a 200 cell cat on there and I just wanted to finish it all off. take it they were tellin porkies?

Yes it is correct. I worked there for 10 years but got pinched by the online retailer MotorSportWorld to head up the sales and marketing. They offered me a nice package and was a job i can develop and have more future potential. I was as far as i could go at Piper, and while it was a fantastic job, it was time for a change. Im only 27

I would say they are half right. The standard downpipe is ideal for a standard car. But once you start playing with them and running more boost etc, you find the limits of it quite quick. So if you want to modify your car then an uprated larger bore downpipe is a must. Not too big tho

Garry

So you relocated to Scotland then Garry?

Damn... I was wondering if I'll ever get to have a drive of your car again, it was a lot of fun

No mate. Was up there for around 3 months training tho but have set up an office in Ashford, Kent so am home now. (hence not being on here much recently)

All good now tho

Cool I'll have to pop down for a drink sometime

Yes mate. Your always welcome

Did you get your Rack fitted yet?

glad its all worked out Garry mate, thought you had been let go due to the eco climate.

all the best

cheers

billy

Yes mate. Your always welcome

Did you get your Rack fitted yet?

PM Sent, don't want to take the thread off topic