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      12-20-2021, 09:40 AM   #1
NGROSSO
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M6 tuning, exhaust, down pipes questions

Hi all,

Been driving my car for 4 months now and love it. Winter season in the northeast means I have time to sort out my knit-picky things. One being the exhaust. I have Miesterschaft 102mm with Catless dp’s. The thing sounds amazing although for a small town like mine it might be a little much. Turns a few more heads than I was hoping. If I were to test out putting my stock dp’s back on the car, am I really going to lose that much performance and is it a pain for adjusting the tune?
Yes I’m aware catted pipes won’t be as fun overall, but I’ll blend in a little more and be NY emissions legal which would be nice for the ease of things.


I’m running DME S2 which means I should be getting around 690whp. I always understood catless dp’s meant 30-40+whp but after doing more research, on a 700hp car it shouldn’t be more than 3-5 with proper tuning.

Secondly, I get an annoying exhaust rattle in low rpms *sometimes*. Is this a mounting problem with the exhaust or just a result of the catless DP’s?

So anyone have input on the exhaust rattle?, effect on tune if I were to add my DP’s back? And if it might be the more refined sound I’m hoping for? Thanks!
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      12-20-2021, 09:42 AM   #2
NGROSSO
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      12-21-2021, 02:47 AM   #3
20comp8
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Following.
Would like to know hp difference between catted and catless.
I kinda like the idea of being quieter if not too much power loss.
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      12-21-2021, 12:18 PM   #4
HeyKC
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Most stage 2 tunes require the catless DP. Or at least a high flow cat. I'm no tuner so I dont know why. Does your exhaust already have the controllable valve flaps?

For the rattle I try and find where its coming from. It could be a WG rattle that some speak of.
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      12-21-2021, 02:26 PM   #5
NGROSSO
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Quote:
Originally Posted by HeyKC View Post
Most stage 2 tunes require the catless DP. Or at least a high flow cat. I'm no tuner so I dont know why. Does your exhaust already have the controllable valve flaps?

For the rattle I try and find where its coming from. It could be a WG rattle that some speak of.

Most do require catless pipes for s2 although I heard Dinan talk about his newest S2 and S3 tunes for the s63 and he said it’s all BS more or less. Said if tuned proper you should only be losing 5-10hp compared to catless pipes. Hadn’t heard this before, but would be nice to have my cats on the car if I could get similar performance.

Exhaust rattle appears to be a result of downpipes from what I’ve read.
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      12-22-2021, 02:16 PM   #6
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I'm looking at the Noelle tune. Doesn't require any other mods and bumps my 640i up 105 HP. From 315 to 420. Only thing the shop says has to be done is the oil needs to be Liquid Moly. It has to be done by authorized Noelle shop.
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      01-12-2022, 03:37 PM   #7
Whipple
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Quote:
Originally Posted by NGROSSO View Post
Hi all,

Been driving my car for 4 months now and love it. Winter season in the northeast means I have time to sort out my knit-picky things. One being the exhaust. I have Miesterschaft 102mm with Catless dp’s. The thing sounds amazing although for a small town like mine it might be a little much. Turns a few more heads than I was hoping. If I were to test out putting my stock dp’s back on the car, am I really going to lose that much performance and is it a pain for adjusting the tune?
Yes I’m aware catted pipes won’t be as fun overall, but I’ll blend in a little more and be NY emissions legal which would be nice for the ease of things.


I’m running DME S2 which means I should be getting around 690whp. I always understood catless dp’s meant 30-40+whp but after doing more research, on a 700hp car it shouldn’t be more than 3-5 with proper tuning.

Secondly, I get an annoying exhaust rattle in low rpms *sometimes*. Is this a mounting problem with the exhaust or just a result of the catless DP’s?

So anyone have input on the exhaust rattle?, effect on tune if I were to add my DP’s back? And if it might be the more refined sound I’m hoping for? Thanks!
I actually had Meistershaft exhaust with cats in and is sounds really good, it does quiet down the turbo whistle a bit , you can definitely run cats with a stage 2 DME tune but im not sure how much power you will lose you also have to gap your plugs @.20 with DME stage 2
I heve catless downpipes myself and the rattle you hear is the waste gate clappers in the turbos its perfectly fine ,If you install your cats back it will get rid of that sound

I have Pure Turbos in my car now and they use a new billet waste gate design
that basically eliminates that rattle ,with stock turbos my car sounded like a rattle can of spray paint right before every stop
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2015 M6 Gran Coupe> DME stage 3 tune back end flash>JB4 with Methanol control>Fabworx Catless downpipes>Full Meistershaft GTC exhaust 102mm GB tips>Built motor with Forged Cp Carillo Rods and Pistons > SSP spec X clutch > Stage 1 Pure Turbos>PG front mount intakes>PG charge coolers>Vorsteiner front and rear Carbon diffuser>Auto Tecknic Carbon shift paddles>3D Design aluminum pedals
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      01-17-2022, 11:45 AM   #8
NGROSSO
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Quote:
Originally Posted by Whipple View Post
I actually had Meistershaft exhaust with cats in and is sounds really good, it does quiet down the turbo whistle a bit , you can definitely run cats with a stage 2 DME tune but im not sure how much power you will lose you also have to gap your plugs @.20 with DME stage 2
I heve catless downpipes myself and the rattle you hear is the waste gate clappers in the turbos its perfectly fine ,If you install your cats back it will get rid of that sound

I have Pure Turbos in my car now and they use a new billet waste gate design
that basically eliminates that rattle ,with stock turbos my car sounded like a rattle can of spray paint right before every stop

Got it, thank you. This makes sense. Might just have to go with pure turbos then
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