Exhaust Dilema

Have you tried the same setup but with stock cats? Should reduce the volume noticeably

 

Yes, put the oem cats back on

 

AP headers are the cause. Loss of pre-cats really increases the volume.

 

S-Line exhaust is not the cause for sure, AP headers + high-flow cats are the ones that make your car super loud.
And I believe AP headers is louder than Fabspeed headers also.

 

Two sets of MKIIs? Both sets began to rattle?? How many miles/years they lasted?


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I replaced the manifolds with a Capristo set and their insulation covers. Normal driving about on the auto box and not much difference but it does tone up well when pushing on using the paddles without being so loud it drives u around the bend. You mention you had used 3 sets of manifolds which i find hard to understand, do you replace the original brackets on the gearbox with something like Capristo expansion brackets.? The expansion on these is huge and the OEM brackets are useless in managing this.
These manifolds get very little ventilation to disapate the heat when driving slowly, it uses holes in the undertray to scoop up air but if you run it at high revs in low gears then you dont have enough forward speed to scoop up sufficient cooling air, after all the heat has to go somewhere.
You have been lucky that these failed manifolds have not been sucked back into the engine on the over run.
If u r running cats with low cell count then it is going to be loud, i think OEM is 1200 ? but some aftermarkets are only 200, not much more than straight through. The lower the back pressure resistance the higher the exhaust temperature as the engine exhaust is less restricted and higher hp.
You can easily see the difference in position of my exhaust between hot and cold on the Capristo expansion brackets, at least 10 mm

 

As i now understand things you have installed AP manifolds which i am not familar with, i take it these are pre cat free. If that is the case what is the problem re installing the OEM main cats, as this gives you the benefit of the non OEM manifolds and the noise reduction effect of the oem cats. Any cat is better than no cat if just to help reduce the 120db level. I have the Capristo manifolds and the rest is OEM, just enough without the silly noise and they work fine.

 

Try the search function (have to spell Kreissieg properly or you only get this thread):

http://www.ferrarichat.com/forum/search.php?searchid=9716108

I think there are several firsthand accounts and some video/sound clips herein.

 

Yes, they are made by the same company in Taiwan.

Do you have valve controller? I currently run stock exhaust with IPE header. It is quite, when the exhaust valve is closed. It is too loud for me when the exhaust valve is open. A lot of people that said their setup is quite around town is because the valve is closed when you drive around town which usually under 3500 rpm.

I'm going to dyno my car today with the header and stock exhaust, with the valve open and closed. Then I will dyno again when I put my stock header back to see what's the difference and if there are any HP gained worth the loudness.