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Discussion Starter #1
Hi , apologies if this has been covered- have tried a search,
I have a 2.0ts p1 which io am really pleased with :)

have recently replaced the last 2 exhaust boxes i.e the backbox (transverse) and the little box on the tail pipe with straight pipe so am left with the cat ,smallbox straight after the cat and main box(all oem boxes)

my query is ;,

-is it worth taking out the small box after the cat ? is it a straight through type? would i get a bit of resonance ? ,

on a side note is there any way of altering(adjustment screw)on the fuel/air mixture on the afm?
also -obviously no e easy way to adjust ignition timing as its coil packs i guess?
anyway thx for any responses !
oliver
 

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I think you'll find that fuel mixture and ignition are all controlled by the CPU ............. If you want any changes to them you will need to get a remap............... Don't try playing with it yourself 'cos you'll ***** everything up....... get a professional on it (anfd let them ***** it up) ..........

........as for taking out the silencer boxes ......... it'll probably be a bit noisy ............ and you will probably have pengine / performance issues ...........cos an engine needs a bit of "back pressure" whick these boxes provide.

But then I could be totally wrong !!!!

Cheers to All
Peter
 

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On mine I took out the saddle box of the rear section, the front box, so left with the tear tail pipe box and main centre,

The front box did not make much difference, the saddle box is the most restrictive

if you looking to increase performance then you need free flow systems like, powerflow, longlife, raggazzon, ect

no there is no way of adjusting the mixture the ecu does that,

if your looking for a remap then do all of the mods first,
 

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Removing the centre box will give the biggest noise increase out of all of the boxes. I personally - and I like loud exhausts - would not remove the centre box. If you want louder then concentrate on the end section.

Regarding backpressure issues: there are a lot of conflicting thoughts on this. I believe that any backpressure is simply wasted energy. Why do some of us spend lots of money on less restrictive exhaust parts? To improve exhaust gas flow, thereby improving power, is the answer. Restrictive front pipes, catalysts and exhaust sections only serve to make the engine work harder to expel exhaust gases. This wasted energy could be used to push the car forward rather than push gases out.

Modern engines, with ECUs, compensate for the reduced backpressure by adjusting fuel/air values. This is not possible with older, carburetted engines, which probably led to the many nightmare backpressure stories, most of which described knackered exhaust valves and engine faults.

I'm more than willing to hear other opinions on this. ;)
 

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Exacly stormvr6 the second mid box part of the rear section is the worst part of the exhaust, and on the later models the pre cats,

but the main thing is to just smooth out the flow which will give you performance
 

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Discussion Starter #6
thx for the replys ,
on previous cars ive had good gains well few "cheep" bhp from freeflow exhaust /induction touch of a ignition timing advance but looks like a remap is the best option
i think the standard exhaust seems elaborate/too many boxes , prob leave the front box in reading your comments (itacarboy) , hows the sound level btw?
cheers
 

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I had a loglife system made for mine................. it's given it a nice crisp exhaust note .......doesn't howl on the motorway.

I'm not sure it's made any difference to the performance, maybe it has or maybe my brain thinks it shoul so I think it has.............. but for sure, it has made the car much more driveable, smoother and it took out the slight jerky hesitation that the engine had when pulling away. Worth all the pennies.

Cheers to All
Peter
 

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the noise level was just, a perfect note, its not loud, no noise on motorways, just a nice sound
 

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Lewis at alfa technico told me today that the cat on early gtv's is very restricive and de catting can give over 10bhp, sounds interesting.
 

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There's no real performance gains to be made from a "free flow" cat-back system. If you're still carrying the OE front pipes and cat then it's only the exhaust note that's going to change. It's like adding a piece of hosepipe to a straw and expecting to suck more water from a glass.

A whole new system (front pipes, sports cat and exhaust) may give a 10+bhp increase, but on a 220bhp car like my V6, an extra 10bhp is barely noticeable, if at all to most people. What is noticeable is the increased torque, which isn't exactly a strong point on the GTV V6. It's that extra torque which makes all the difference for me, and really shows off that the engine is breathing more easily.

Only when a full performance exhaust is fitted and the engine is pushing out gases quicker - hence sucking more air in - is it really worth considering an upgraded intake. Otherwise you're only gaining extra noise, again.
 

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I disagree a performance exhaust on a early Gtv up to 2001 you will notice a differance in lower end torque, later models have pre cats which is more important to remove as they can be up to 5bhp loss each,

the early models have a decent Mani and down pipe, if you could afford it then yes fit a sports cat, to go with the system,
 

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I disagree a performance exhaust on a early Gtv up to 2001 you will notice a differance in lower end torque...
I'm not certain what you're saying, but if you mean torque is improved then I did say that here -
What is noticeable is the increased torque...
Although I still stick by my previous comment that a cat-back system gives no real performance gain. On the TS you'd being looking at 1-2bhp at best; totally unnoticeable. The system will definitely breathe slightly easier allowing for slightly better lower end torque, but still, it would be a negligible amount on the TS, even the V6.

I believe most people, after having a cat-back system fitted, feel a performance gain due to the added noise, which generally leads to a heavier right foot. A placebo effect if you will.

Just my opinion by the way. ;)
 

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exhaust and induction technology is indeed a mysterious subject,........ therefore gentlemen i propose to conduct an experiment!......, just on my way to noble motorsport to measure bhp/torque, the only mod to the system i am aware of is a jpx stainless rear exhaust, had a new air filter fitted (lazy) yesterday, so the system is not far from standard, so depending on the results (ie if its got compression probs i'll sell it! if its not too bad i'll start mods to improve it) i will initially fit a straight thru mid box and also de cat, then dyno test again, we will then know what difference it made, then i will mod the induction system and measure again, finally i will have it re-mapped and again measured, that way we can put to bed any myths/theories and either get some improvements or save everyone else money, cars are my hobby so i justify any expense under that banner (to the missus), wish me luck gentlemen im off to the lab,.... i may be some time.
 

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Guys

I need to replace the little tailpipe: the tube between it and the last silence has broken. Any idea on costs? And should I go to dealer or indie?
 

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Very pleased, its making more power than it should, dynoed at 153 bhp and 137 lbft torque, amazing as the engine has done 125,000 miles, Noble motorsport are now doing some digging as to the best way to go, good service cos it'll save me searching, he thinks de catting, induction and a re map to suit will give a lot more torque and up to 20 bhp, watch this space.
 

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Very pleased, its making more power than it should, dynoed at 153 bhp and 137 lbft torque, amazing as the engine has done 125,000 miles, Noble motorsport are now doing some digging as to the best way to go, good service cos it'll save me searching, he thinks de catting, induction and a re map to suit will give a lot more torque and up to 20 bhp, watch this space.
That really is impressive for an engine that has done that many miles. Goes to show how good they can be when properly maintained i guess?
It will be interesting to see the gains you get from your planned mods.:thumbs:
 

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Very pleased, its making more power than it should, dynoed at 153 bhp and 137 lbft torque, amazing as the engine has done 125,000 miles, Noble motorsport are now doing some digging as to the best way to go, good service cos it'll save me searching, he thinks de catting, induction and a re map to suit will give a lot more torque and up to 20 bhp, watch this space.
You've got a very strong engine there mate, congrats!

A de-cat, induction upgrade and remap will improve the torque considerably. An extra 20bhp on the TS with those mods isn't out of the question either. You could even gain slightly more.

Hope it works out for you. :thumbs:

Sorry jjlehto: we don't mean to hijack your thread. But it's all free research towards your question.
 

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Discussion Starter #19
no worries at all its exactly what i wanted to know , i might go with a decat having read this
atb and those mods sounds like a nice setup ,!
 

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cheers, yeah over the moon with that result, lewis at AT had driven it and said it seemed ok, but i hadn't realised it was that ok!, so looking fwd to trying to get even more out of it now, especially torque as stormvr6 says.
 
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