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06 CTS-V
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Discussion Starter · #1 ·
Does it really make a difference, 1 3/4 vs 1 7/8? I just turned down a pretty good deal on a brand new set of Kooks/cats because they were "only" 1 3/4. $900 brand new in the box. The Maggie goes on this week and I just want to make damn sure I'm getting everything out of it. It's also getting the 10% harmonic balancer,which should push boost up to 10 lbs or so. As I understand it, the rule of thumb is blower=wider headers. I know this has been argued before but I'm just looking for reassurance before I whip out the plastic!
 

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'06 Z06, '05 CTS-V 453rwhp/434rwtq (sold)
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If you want the most out of the maggie, get the larger ones. I would have if I were doing it again. The more air you can get in and out of your engine the better. Especially with how you're boosting it.
 

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'06 DTS performance; CowboyCadillac='12 SVT Raptor; 2014 XTS-Vsport
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634 Posts
:cynic: Do not expect 10 lbs. of boost from a MP112, especially with headers.
:coffee: Be happy with 8lb. to 9lb.
It's about 'Density' not 'Pressure'. :wisdom:
 

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04' Blown CTS-V 554rwhp 497rwtq
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If you want the most out of the maggie, get the larger ones. I would have if I were doing it again. The more air you can get in and out of your engine the better. Especially with how you're boosting it.
Well said. I run 1.75" B&B and couldn't be happier though. In all the research I've done/heard if you haven't purchased headers yet go for 1 7/8. If you have 1 3/4 already then don't worry about it.
 

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Discussion Starter · #5 ·
:cynic: Do not expect 10 lbs. of boost from a MP112, especially with headers.
:coffee: Be happy with 8lb. to 9lb.
It's about 'Density' not 'Pressure'. :wisdom:
OK-even with the smaller harmonic balancer? I was told to look for 10... more importantly, how much do the wider headers play into the equation?
 

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Discussion Starter · #6 ·
Well said. I run 1.75" B&B and couldn't be happier though. In all the research I've done/heard if you haven't purchased headers yet go for 1 7/8. If you have 1 3/4 already then don't worry about it.
Its my last purchase as Miss Maggie arrives on Wednesday. Mights well go with the wider ones, though. Just makes sense-wider tube gonna allow more gas through, especially with underdriven balancer. My installer is not fond of 1 7/8 headers because they just occupy more space in an already cramped engine bay! I'm also leaning toward ceramic coated, also.
 

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04' Blown CTS-V 554rwhp 497rwtq
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OK-even with the smaller harmonic balancer? I was told to look for 10... more importantly, how much do the wider headers play into the equation?
Boost is a measure of restriction only and not what you need to be concerned with. If you can have 550wrhp and 5 pounds you are further ahead then 480wrhp and 10 psi...

Anytime you change the flow characteristic of the motor (better flowing heads or larger headers etc) you will drop boost psi but make MORE power. Thats a good thing.
 

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'05 CTS-V, '00 SLS, 98 SLS, 89 Eldo, '80 Eldo
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:negative:
Hold on. Did anyone notice he said underdrive pulley. OP you need an overdrive pulley. 10% bigger, not smaller for more boost.

And yes. With an overdrive pulley and headers you'll see about 8# of boost. But you'll still be flowing more air than I am with a 2.6" Maggie drive pulley and stock manifolds which gives me 10# of boost.
 

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04' Blown CTS-V 554rwhp 497rwtq
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Hold on. Did anyone notice he said underdrive pulley. OP you need an overdrive pulley. 10% bigger, not smaller for more boost.

And yes. With an overdrive pulley and headers you'll see about 8# of boost. But you'll still be flowing more air than I am with a 2.6" Maggie drive pulley and stock manifolds which gives me 10# of boost.
True. Although I think he is having someone put it all in for him so hopefully they wouldn't under-drive him!
 

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389 Posts
Go for the 1 7/8", there is a difference....esp when boosted. GO ahead and get motor mounts now, you will have to remove the headers to replace them later. Ask me how I know :banghead:
 

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'06 DTS performance; CowboyCadillac='12 SVT Raptor; 2014 XTS-Vsport
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OK-even with the smaller harmonic balancer? I was told to look for 10... more importantly, how much do the wider headers play into the equation?
:coffee: 1 3/4ths vs 1 7/8ths: you will get a slight movement of your torque curve to the higher RPM and you will get a very slight reduction in boost pressure.
You will not feel :burn: or notice the difference, but you can measure it.

:yup: Like Twitch said, Larger pulley at the crankshaft on a maggied engine to spin the maggie faster for more boost.
* good eyes Tony . . a least your brain is engaged when reading . . . . .
> "when I thinks ~ I falls asleep" < ~:yawn:~
 
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