exhaust dilema

[quattrosteph]

Difference between resonated and non-resonated : between downpipes and the rear box (2 of them) there is 2 tubes called link pipes, the non-resonated are simple tubes , the resonated ones are the same tubes but with on the inside a double thickness filled with wool steel (it is like 2 mini silencers...) it does stop the drummie sound when you cruise.

i don't know if some of you go often to a rolling road but gutted precats + milltek back box+remap do not increase the power to 450 bhp!!!!!!!!!

In the real world between 430 to 435 bhp maximum !!

to go near the the 450 you need to run no cats at all ... or you need to have the boost increased a lot .

[Newdub]

Do you need to run an aftermarket ecu if you ditched the cats all together?? ( because of the maf ) Sorry to go slightly off topic

[jimbo1234567]

eh!

[Newdub]

With some cars (usually older) i know you can by pass the cats =more power,,,, on some cars i believe you need to run, for eg a plug and play ecu(autronics,tech3,motec,etc)as to avoid the fact some ecu's dont like the strange lamber readings it would send back with no cats???? i think..... i might have it all wrong hence the question? hopefully someone with a lot more knowledge than me will shed some light on it

[clived]

Difference between resonated and non-resonated : between downpipes and the rear box (2 of them) there is 2 tubes called link pipes, the non-resonated are simple tubes , the resonated ones are the same tubes but with on the inside a double thickness filled with wool steel (it is like 2 mini silencers...) it does stop the drummie sound when you cruise.

i don't know if some of you go often to a rolling road but gutted precats + milltek back box+remap do not increase the power to 450 bhp!!!!!!!!!

In the real world between 430 to 435 bhp maximum !!

to go near the the 450 you need to run no cats at all ... or you need to have the boost increased a lot .

I'm running 100cpi Milltek cats, and I got 448.5bhp that day at the Silverstone RR....

[neckarsulm]

Ah Bugger! lol, Non resonated can be droney at motorway speeds (well sensible motorway speeds!) whereas ressonated isnt.

My early (2002) non-resonated can be boomy at 30-60 but when cruising at 70 upwards it's nothing compared to the usual wind and tyre noise. However its rarely annoying, not even to my wife who has a low tolerance for these things and when given the berries it sounds great - thank god for the Queensway tunnels in Birmingham!

[quattrosteph]

Difference between resonated and non-resonated : between downpipes and the rear box (2 of them) there is 2 tubes called link pipes, the non-resonated are simple tubes , the resonated ones are the same tubes but with on the inside a double thickness filled with wool steel (it is like 2 mini silencers...) it does stop the drummie sound when you cruise.

i don't know if some of you go often to a rolling road but gutted precats + milltek back box+remap do not increase the power to 450 bhp!!!!!!!!!

In the real world between 430 to 435 bhp maximum !!

to go near the the 450 you need to run no cats at all ... or you need to have the boost increased a lot .

I'm running 100cpi Milltek cats, and I got 448.5bhp that day at the Silverstone RR....

It is really good mate you still 1.5 bhp too short !!! I know some cars give more than others with exactly the same mods, i think you are running a little bit more boost to reach 448.5 bhp?

[ewill]

Ah Bugger! lol, Non resonated can be droney at motorway speeds (well sensible motorway speeds!) whereas ressonated isnt.

My early (2002) non-resonated can be boomy at 30-60 but when cruising at 70 upwards it's nothing compared to the usual wind and tyre noise. However its rarely annoying, not even to my wife who has a low tolerance for these things and when given the berries it sounds great - thank god for the Queensway tunnels in Birmingham!

My experience was the same for the newer revised resonated system. Unacceptably loud IMO. I got a local manufacturer to replace the back box with one of their straight-through units, and now its perfect. As much noise as you want to hear when pootling but no more, and still the amazing noise when you give it stick and no discernable loss of performance. Its the system that Miltek should have built in the first place IMO.

[R5YUG]

I think it all amounts to personal preference over the noise - for me I like to hear a little exhaust note so I'm going for the Non-Res Milltek's next month.... I'll be taking the RS4 to Worthersee this year so I'll soon find out if I can get on with any excessive cruising noise.
...there is always the BOSE to drown that out

[SimonC]

With some cars (usually older) i know you can by pass the cats =more power,,,, on some cars i believe you need to run, for eg a plug and play ecu(autronics,tech3,motec,etc)as to avoid the fact some ecu's dont like the strange lamber readings it would send back with no cats???? i think..... i might have it all wrong hence the question? hopefully someone with a lot more knowledge than me will shed some light on it

Lambda (oxygen) sensors are upstream of the cats so shouldn't be affected by cat-removal.

I think some early efi cars ran lean if you put a free-flowing exhaust and filter on them, necessitating a re-chip.

[gb]

This is really helpful discussion for a new commer like me. I have seen no dicussion about custom downpipes, guys - has anyone come across such items with a greater than OEM diameter ?