The exhaust on my 'new' 4 is 80mm, where the exhaust is routed over the rear diff, its rattling (its a really tight fit).

Do I:
Change it for my old 4 exhaust (stainless mongoose 2.5") - will this affect the mapping i've just had?
Tap the areas it's hitting with a mallet (as its a mild steel jobbie)

The 'new' 4 needs a bung in the end as it's bleeding noisey
My old 4 exhaust sounds great - much better and not so loud and it's better quality.

so what do i do ... err i dunno?

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ST205




"And God said, Let the earth bring forth grass, and the earth brought forth grass and the Rastafarians smoked it."

Difficult one - switching the exhaust is going to affect the mapping you've had done - but then again so is putting a bung in the existing exhaust.

I'd be tempted to have the exhaust swapped - then have the map tweaked to suit.

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GT4DC Events Co-ordinator
1996 ST205 UK

Reducing teh CSA or addinga bung is likely to add more restriction at high boost/rpm and hence more of the hot spent gases will stay within teh combustion chamber/less new fresh air/fuel mix. As such it is likely to be more prone to det (remove some timing) and less air per bang therefore reduce the fuelling. Et Voila - one new remap!

IMHo for now I would look at
a) tap exhaust in teh area where it go's over the rear axle -(even hayward & scott had to do thsi slightly on mine - or alternatively tweak teh crossmember it si hitting - only oressed stell)
b) Add additional sound deadensing in teh boot and rear seat area - remove when on track - I know Kris has added this and is surpringly effective.

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JP
GT4DC Treasurer

Grey St185 RC
Silver BMW E46 M3
Multicolour yawn Honda VFR400
Silver Honda Civic Type-R

Exhaust wrap is your friend

It will stop the rattling and help to dampen the noise a little (although it won't cure it by a long shot). Keeping the gases hot might mean less going out the back of the tailpipe and it will dampen out the pipe resonance a little . Especially if you paint it to stop it smoking when raining (although it will smoke like a smokey thing down the pub until the paint dries)

If it's just going to be a track toy then I'd suggest leave it be

I'm going to tap it and wrap it then take out the bung and see how it sounds.

I've seen some waterproof exhaust wrap - anyone got any experience of this?

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ST205




"And God said, Let the earth bring forth grass, and the earth brought forth grass and the Rastafarians smoked it."

Didn't even know there was such a thing Rob

http://www.cooltek.co.uk/exhaust_heat_wrap.htm

and
http://www.sesametech.com/automotive.htm

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ST205




"And God said, Let the earth bring forth grass, and the earth brought forth grass and the Rastafarians smoked it."

solved the problem with a small hammer and some heat. I adjusted the rear exhaust mount to lift the tail pipe as it was fouling. NOw it's bloody close to the bumper - do you think this'll melt - should i get some kind of ally to protect the bumper?

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ST205




"And God said, Let the earth bring forth grass, and the earth brought forth grass and the Rastafarians smoked it."

If it's the very end of the tailpipe you should be ok Rob.
I suppose you could always stick a piece of heat reflective material onto the surrounding area....depends if your fussed about the looks?

My new exhaust is pretty close....luckily not knocking yet....and no melting plastic.

Steve

It's not quite touching about 2mm away. If i get some black protective plate - it won't look too bad i think?

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ST205




"And God said, Let the earth bring forth grass, and the earth brought forth grass and the Rastafarians smoked it."

If your car is black then it'd barely be noticeable, at least you'd know it's there for a purpose rather than the looks.

Rob > I'd get a bit of thin metal, trim and bend to fit, paint it black then bond on by the zorst. This'll protect the bumper and fit in with your stealth looks

As for noise, I've got JP's old Aussie with the bung removed. It was rather loud so I had the resonator in the midsectoin replaced with a 3" straight through silencer. That's dampened things down a bit, but it's still a bit much - got some of that audio sound deadening sheeting which will be going in the boot when the weather clears up and I get a chance to sort it

Failing that, a bit of cotton wool in your ears will help

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'92 GT-Four RC - Project Rufus - something of a mover.
'05 Audi A3 3.2 V6 Quattro S Line - not bad for a daily.

Now that i've bent and reshaped the exhaust, it's still resonating on the 4 point lower brace, i suspect it could be the engine movement, there is about 5-6 mm between the brace and the exhaust, any ideas - should i look to fit an after market engine brace?

Thanks for the tips guys - cotton wool is always inserted as i like to avoid wolf whistles as i walk along the street

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ST205




"And God said, Let the earth bring forth grass, and the earth brought forth grass and the Rastafarians smoked it."

Consider some TRD engine mounts maybe?

OR see if Andy has had any joy with his DIY poly creations. You might just be able to stiffen up stock mounts

Otherwise something like an old gixxer steering damper or similar might prove useful

Would a steering damper do the job though - i was under the impression that engine braces were pretty static?

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ST205




"And God said, Let the earth bring forth grass, and the earth brought forth grass and the Rastafarians smoked it."