[9ines]

My RSB cat-bat muffler has a hole in it and needs to be replaced. Does anyone have the specs on this so that I can buy a new one?



thanks,

-kb

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[banditsc]

Dynomax 17749 Super Turbo http://www.amazon.com/dp/B00029J3ES/ref=...s_sce_dp_1

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[9ines]

[quote name='banditsc' timestamp='1331563027' post='123174']

Dynomax 17749 Super Turbo http://www.amazon.com/dp/B00029J3ES/ref=...s_sce_dp_1

[/quote]



Thanks!

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[DaveN]

How long have your had your system? As it SS I hope the hole was from a puncture or a failed weld not rust.

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[flash]

isn't there a lifetime warranty on those?

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[banditsc]

[quote name='flash' timestamp='1331568942' post='123183']

isn't there a lifetime warranty on those?

[/quote]



Yes, there is..

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[bombfactory]

The pipe from the cat to the muffler might be stainless, but the Dynomax muffler certainly isn't. Mine had what sounded like a hundred rusty metal pieces rattling around in it, so I took the whole thing off.



I will be having the resonator restrictor plate removed from my stock exhaust soon. Will report if there's any difference or, hopefully, improvement.

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[flash]

i would not do that without driving one that has it done first. i drove a car that had that done (here local too). while i think there was a bit snappier response up top, though i can't say it actually had any more power, it felt a bit softer down low. that may or may not make you happy

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[bombfactory]

Boy, no mod is ever a slam dunk with these cars! Flash, can you confirm that this plate was added to US cars only to meet DOT sound requirements (as I've read elsewhere)?

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[Cloud9...68]

"Boy, no mod is ever a slam dunk with these cars! "



It isn't just this car. It's actually a bit of a challenge to do anything but the most basic mod on just about any car newer than about 1990, as the manufacturers go to a lot of effort to create a product that provides the best compromise of performance, comfort, and cost (both purchase price and operating cost), within the parameters of laws and regulations. Generally, when you modify something to improve one aspect of the car, you end up degrading something else. It's a quesiton of your tolerance for the thing you've degraded, vs. the pleasure you derive from the thing you've improved.

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[flash]

no idea where you are reading that, but it sounds like more misinformation, perhaps started by a 944 guy assuming that a 968 is like those.



if anything, germany would have had much more strict sound regulation. theirs is the tightest in the world. based on that, i would say it is in all of the cars. i have seen no difference whatsoever in the exhaust systems between ROW and US cars (other than the cat-delete cars in countries like south africa)

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[bombfactory]

Wow, hard to believe that plate doesn't just kill the flow completely. If anyone here has done this mod, can you post your before/after impressions?

   

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[pure&simple]

Mine was replaced for free under warrantee. Just give Pete a call and he'll send you a new one.

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[craigawoodman]

That plate must restrict flow. How do I know, because I have a different problem with mine - it is slightly larger and more free flowing than when supplied. It is likely that when the car was being initially tuned - too much fuel was allowed to get into the exhaust system. As there is no Cat (there is a pipe but no Cat in the system) - we are assuming that there was a fairly large backfire - and the exhaust took most of the pressure and is expanded (split the seams). So does the baffle restrict flow - um - yes.

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[Byte]

I don't remember seeing that plate on mine. Hmmm.

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[bombfactory]

There has to be a good reason why Porsche put that plate there. Flash states that the regulations for muffler noise are more strict in Germany than they are here. If that's true then the idea that the plate was added to US cars to meet DOT regulations is most likely not correct.



My guess is that the plate slows the exhaust gasses to whatever velocity Porsche thought was the best compromise between low to midrange torque and hi-end power.



The question is, what effect would removing the plate - or maybe just enlarging the two oval holes somewhat - have on power delivery? My only engine mods are a RacerX chip and the airbox mod. I'm sure the car could benefit from better breathing at the higher rpm's the chip allows, but how much, exactly, before the low end suffers?



I need to run this by an exhaust engineer friend of mine...

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[flash]

lol - welcome to the slippery slope of exhaust mods. been there done that. i threw $11k away trying to work this one out. pete did another $10k or so. we're having jackets made next week.



basically, there is no free lunch here. when you open up the exhaust, you start losing lower end torque. how much and where is relative to the mod.



the annoying thing is that there is always a dip in the mid 3k range that happens when you open it up, and that is right where most people don't want it



i have only driven one car that had the mod you are talking about, and while it seemed to have slightly better throttle response, particularly up top, it seemed a bit softer down low. to be fair though, i did not drive that car before the mod, so it might just have been a softer motor. even the owner though only claimed 8hp even with a chip, so i tend to think he actually lost power with the mod, since the LOWEST power increase with any of the chips i tested was 7. the throttle response may have been there, but still with less power.



have fun

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[bombfactory]

Flash I told Phil last night to leave the plate alone - not going to touch it for now.



On a related note though - well, maybe not so related, as conventional wisdom often falls on its face when applied to the 968 - I've added the S50 intake manifold (much larger runners) to my S52 E36 M3 (in addition to headers and a cat-back), which is supposed to cost some midrange torque. But with software and a lightweight flywheel, I don't feel like I've lost anything. The car has plenty of midrange, but now pulls to 7000 whereas before all these mods it would completely run out of breath at about 5500.



Perhaps a similar equation could work on a 968 - the airbox mod and software offer proven gains, add a lightweight flywheel to kind of 'patch' the low to midrange losses introduced by going to a freer flowing exhaust. Better throttle response would definitely be welcome on this car. Boy, second-guessing Porsche engineers ain't easy!

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[flash]

lol - yeah - i did all of that



just remember that there is no free lunch, and no matter what mod you are considering, it is smartest to do whatever will suit you for the 85% of the driving you do, whatever that is. if 85% is track, then you would do one thing. if 85% is sitting in traffic or commuting, then it's entirely different.



p.s. - been trying to reach phil. he pinged me to call him, but has not been answering the phone

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[bombfactory]

Hopefully he's under my car right now and can't reach the phone :-)

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