Let the tinkering continue.....

i still reckon not spend more money than you have to on a special muffler - i mean, if its $150, sure, but if its more than a few hundred, i cant see you getting hte benefit. your little GT17 is the best muffler in the system and your keeping it there.

on another note, although i agree that shorter is better, you will likely not enjoy having a pre-tailgate exhaust dump.... without the DPF and with a hotter tune you will make more smoke (if only on throttle transitions) and it will make your car dirty :-)

you made a mention about the turbo outlet transition - i'm not sure that this part of the system is all that important. gas flow from the turbo is so fast and so hot and turbulent that even undergoing step transitions (from smaller to larger cross sections) has a minimal effect on flow. another place you might save some money to put towards something else of greater benefit (In my opinion).

HTH, glad its all going well :-)

Quote:

---

Originally Posted by cogdoc

So I've got a 2.75 dump, and a stock 2.5 system. Given larger cat back exhausts never liberate much power ( if any! ), as the gas has cooled, and it's the hotter downpipe flow that matters, I'm thinking of sticking to the stock cat back, adding a custom resonator only, and dumping it to the road at the rear axle area. Shorter, and basically straight, should flow ideally.

Still keen on one of those Aero muffs, but they recommend putting it up as close to the front as possible in a diesel, given the lower temp gases, so I'm stuck between choosing a 3" to be as low a restriction as possible with a 2.75" pipe in, or simply a 2.5" unit. They are absolutely straight through, but all the research I've done shows they are both living up to the hype of helping flow, hp and MPG, and quieter than anyone would believe. I'm going to commit to an exhaust plan this week, so any ideas otherwise????

---

I found an interesting exhaust system for the Octavia's on the superskoda website - http://www.superskoda.com/Skoda/OCTA...h-TITANIUM-TIP
I mean it's not designed for your engine apparently, but it does show that a cat back exhaust may actually release some improvement from the VW diesel engine (skoda RS runs the Golf GTI motor) but have a look at the dyno page. It might all be marketing hype.....??

OK, thanks for the input guys!

Re the Skoda pipe, interesting find, but I find it VERY hard to believe a cat back would liberate more than a few real kw at best. This is the same 2.75inch size as the Milltek, and equally expensive, but if my stock TDi is putting out 113kw at the wheels at the last dyno meet, I can't believe the jump to 137kw or so. Perhaps it's just the Skoda, but more likely an optimistic dyno? I bet my car on that dyno would run 130kw, and I'd expect a bigger cat back to liberate 10kw at best with a DPf still in place. Could be real, but for 800 euro, I'd rather spend $400 au on a Aero muff which of all the stuff out there looks like it may actually have a performance benefit.

And despite your wise words Aydan, I've just ordered a 3" resonated aero muff. Been having long discussions with Parleys diesel in the USA, where I got the snow kit from, and they've got a lot of experience and dyno work with these muffs, and I am impressed with their customer service, knowledge, and absolute keen-ness to assist me in my crazy ideas.

So now I'll be running the 2.75" delete kit dump pipe, into a 3" Aero mid muff, and probably the stock cat back down to the rear. Good point about dirty backs of cars mate, but it's going to dump like the 103kw does onto the road, and if I can avoid the bends around the rear "axle" area to aid flow, well I'm gonna! The alternative is a 3" all the way back and over the "axle", but given the expense there, and the likelyhood of no power difference, I can't see the value.

Gonna be a big couple of weeks!

Make sure you take pics of all the DPF Delet & Exhaust work you do, I'll be very keen to check out your set up! :)

Hi Cogdoc

I'd reccomend "Custom Exhaust Specialists" in Brisbane. They are in Meadowbrook on the southside of Brisbane. I had a custom exhaust done for my old Pulsar sss and the quality of work was second to none. Do a search in google.

Quote:

---

Originally Posted by cogdoc

A Provent will definately prolong the life of your DPF. Simple fact that VW themselves state it fills up eventually due to non burnable oil ash amongst other things. $5500 is the full VW Australia price someone on here mentioned.

Ludicrous huh?

---

^ Good advice, considering the replacement costs of the DPF.

Thanks to others who answered my previous post, you have definately given me something to think about there, especially in relation to service procedures and what maintenance VAG recommend for their diesels.

Thanks for the recommendation of CES, I had indeed heard of them, and they are a possibility. The problem will be getting the dump pipe fitted, the custom code tune done, alongside an Aero muff and subsequent "cat" back. Might have to be someone close by to wherever the dyno tuning takes place, most likely Brisvegas. Have had some great recommendations from my first post on Boost cruising, which has been pleasant to see.

I think this thread has almost run it's course, and become a bit of a intake sludge thread ( which is fine and very necessary ) so once the parts start arriving and getting put on, I think I'll start the " Let the tinkering conclude" thread. Amazing it's almost been 2 years since the "tinkering" began!

A query on boost cruising has a few recommendations for Exhaust Innovations at Capalaba. Sounds like the man for the inlet, if not the exhaust as well. Pleasantly suprised with the help "over there".