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996 GT3 Cat bypass

ditchvisitor

Well-known member
Joined
9 Oct 2017
Messages
346
I've made the mistake of hearing what a 996 GT3 sounds like with cat bypass pipes fitted and am looking around to see what is available.
Does anyone have any sat around that they aren't using, or recommend which ones to get?
 
Where did you hear that?

I've had straight out from cat which sounded awesome but you get a noticeable drop in low down torque but get it back at the top end. Which is great for a few months but then frustrating
 
seconded. if its a road and occasional track car then don't bother. low end it will be rather gutless.

if a race car and you are spending your time at the top end then great. and get it mapped for that

according to Wayne Schofield (Chip wizards) who knows a lot about tuning NA cars he said don't bother for road going GT3s.

the OEM GT3 exhaust system is heavily optimised for exhaust gas scavenging according to wayne and changing this really does play around with how the engine reacts and then drives.

maybe look at 200 CELL cats at best? and then get it re mapped with the IPD plenum and 997 GT3 bigger throttle body?
 
https://youtu.be/JOCPwHdS-5E

This video! I was more concerned about it making a bit more noise more than anything else, it's recently had new OEM mufflers etc
 
it would be so noisy it would drive you up the wall. and your neighbours.

I had this on mine when I first bought it....it had no low down torque and everyone hated me due to the noise.

forget track days too.

you could go 200 cell or 100 cell cats. do you have sports boxes too? if you are oem exhaust they can be quiet ish.
 
NLW73 said:
do you have sports boxes too?

I'm pretty sure it's a standard system, was there an option of a sports exhaust from new?
 
not sure. few after market options.

some decent fabricators out there who can make sports back boxes for you which will have a better sound and flow. maybe 200 cell cats too?

will certainly help with noise and flow but not be bonkers loud.

I used Viper Exhausts in Essex and run by former F1 exhaust fabricator.

i think Top gear exhaust do a full system with headers for a Gt3.
 
I have a M+M Exhaust on my MK1 GT3.

M+M make exhaust's for Manthey and a few of the race teams.

great quality -

http://www.m-m-germany.de/

:thumb:
 
Ditto Dan, it's also a plus on resale. There are also some very good full systems in the US right now.
 
I have the MM full system on my K400 - 100 cell cats, equal length headers, the x-cross over and the sport boxes. I love it. Sounds lovely. I get thumbs up everywhere.

No chance to make it on to a track day though at Brands for example...

So be careful what you wish for...
 
Cheburator said:
I have the MM full system on my K400 - 100 cell cats, equal length headers, the x-cross over and the sport boxes. I love it. Sounds lovely. I get thumbs up everywhere.

No chance to make it on to a track day though at Brands for example...

So be careful what you wish for...

The early Manthey K400 exhaust systems differ from the latter iterations.
The early systems utilised Europipe silencers, X pipe and cats along with M&M manifolds. Once the wire wool wadding in the Euopipe silencers has decayed or been blown out, they sound simply epic :

https://m.youtube.com/watch?t=13s&v=w3J8HeIfJwc

The later systems utilized a complete M&M system (using pre-pressed silencer boxes as opposed to the fabricated Europipe items) The system on the yellow car linked to above would appear to have later M&M silencers (idendified by the straight cut tailpipes rather than the slash cut rolled edge Europipe items) though the yellow car sounds as if the silencers are completely devoid of their wadding ... ! ! !
 
Slippydiff said:
Cheburator said:
I have the MM full system on my K400 - 100 cell cats, equal length headers, the x-cross over and the sport boxes. I love it. Sounds lovely. I get thumbs up everywhere.

No chance to make it on to a track day though at Brands for example...

So be careful what you wish for...

The early Manthey K400 exhaust systems differ from the latter iterations.
The early systems utilised Europipe silencers, X pipe and cats along with M&M manifolds. Once the wire wool wadding in the Euopipe silencers has decayed or been blown out, they sound simply epic :

https://m.youtube.com/watch?t=13s&v=w3J8HeIfJwc

The later systems utilized a complete M&M system (using pre-pressed silencer boxes as opposed to the fabricated Europipe items) The system on the yellow car linked to above would appear to have later M&M silencers (idendified by the straight cut tailpipes rather than the slash cut rolled edge Europipe items) though the yellow car sounds as if the silencers are completely devoid of their wadding ... ! ! !

I know the yellow car - remember it having a new rear left control arm being replaced at Ring-Racing after it had kissed the Armco.

Mine sounds about the same - allegedly 107db on drive-by at full chat at Brands (under the bridge into pilgrim's rise and just before druids)
 

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