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      08-28-2009, 01:03 AM   #1
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Question on modifying the stock mid-section.

In this pic (thanks EAS), it looks like the secondary cats are held to the primary cats by band clamps? Is that the case?

Also, does the bracket at the X-pipe support the exhaust there?

Just wondering if one could have a shop to just cut out the secondary cats and X-pipe and replace it with an X-pipe and some piping while keeping the resonators?

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      08-31-2009, 10:31 PM   #2
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Someone must know if the mid-section is all one piece?
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Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."
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      08-31-2009, 10:51 PM   #3
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Yes, the mid-section is one piece
those clamps and support are to hold the pipes to brackets on the car.

You could cut it up and get a shop to make you a custome setup.
A few here have done it
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      09-01-2009, 04:58 AM   #4
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I have done second cats delete x pipe combined with 4 resonators yesterday. I add 2 x 14" magnaflow resonator to slightly cut the loudness and get rid of the drone.

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      09-01-2009, 05:53 AM   #5
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Quote:
Originally Posted by simonlam168 View Post
I have done second cats delete x pipe combined with 4 resonators yesterday. I add 2 x 14" magnaflow resonator to slightly cut the loudness and get rid of the drone.
So how close to stock does this sound? Is the OEM Primary Cat restrictive in its flow?
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      09-01-2009, 07:10 AM   #6
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How much did the magnaflow resonators cost? How you like them?
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      09-01-2009, 07:28 AM   #7
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http://www.m3post.com/forums/showthr...ary+cat+delete
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      09-01-2009, 08:17 AM   #8
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I have Meisterchaft GT2 exhaust with SR pipe installed. It's too loud for normal drive. It sounds almost like Ferrari but louder and the drone is crazy. The drone is annoying me when going uphill. It's much better after 2 additional magnaflow resonators installed. Drone from 2-3krpm is eliminated or at least highly reduced from what it was before.
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      09-01-2009, 08:26 AM   #9
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Quote:
Originally Posted by mixja View Post
So how close to stock does this sound? Is the OEM Primary Cat restrictive in its flow?
I think the sound is more quiet. The resonator is less restrictive than the OEM seoncd cats.

Two magnaflow resonators cost USD130. Parts number 14419.
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      09-01-2009, 04:58 PM   #10
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Quote:
Originally Posted by J08M3 View Post
Missed that one. Four pages and NO DYNO's to see if there's any power gain?
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Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."

Last edited by aus; 09-01-2009 at 05:48 PM..
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      09-01-2009, 07:53 PM   #11
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Quote:
Originally Posted by aus View Post
Missed that one. Four pages and NO DYNO's to see if there's any power gain?
There's definitely power gain if you look at the pic of the inside of the secondary cat and see the restriction.... The question is how much??? To be honest, the car seemed to pull good and strong when I did this and at the time is was combined with an Eisenmann Sport. But measurable power increase was probably minimal. Sound was greatly improved. The main restriction in our systems is the primary cat though. That's the key to increasing power, doing something about the OEM primary.
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      09-01-2009, 08:19 PM   #12
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Quote:
Originally Posted by J08M3 View Post
There's definitely power gain if you look at the pic of the inside of the secondary cat and see the restriction.... The question is how much??? To be honest, the car seemed to pull good and strong when I did this and at the time is was combined with an Eisenmann Sport. But measurable power increase was probably minimal. Sound was greatly improved. The main restriction in our systems is the primary cat though. That's the key to increasing power, doing something about the OEM primary.
I wonder what the sound would be like with ONLY the primary cat delete....

Most people won't do this because you'll throw a CEL but in my case that is taken care of with Powerchip Stage II...

Hesitant to chop up the factory system - but I guess you could always weld the primary cat back on if it didn't work out....

The other aspect of this I'm interested in is whether the infamous torque dip around 2500RPM would be present with just primary cat delete? I.e. would the remainder of the stock system still have enough backpressure to mitigate the torque dip?
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      09-02-2009, 04:31 AM   #13
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Quote:
Originally Posted by mixja View Post
I wonder what the sound would be like with ONLY the primary cat delete....

Most people won't do this because you'll throw a CEL but in my case that is taken care of with Powerchip Stage II...

Hesitant to chop up the factory system - but I guess you could always weld the primary cat back on if it didn't work out....

The other aspect of this I'm interested in is whether the infamous torque dip around 2500RPM would be present with just primary cat delete? I.e. would the remainder of the stock system still have enough backpressure to mitigate the torque dip?
Just saw these from Turner (http://www.turnermotorsport.com/html..._ID=TEN9046MTP) - I guess these would be ideal to do the primary cat delete - anybody got these installed?

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      09-02-2009, 11:42 AM   #14
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Quote:
Originally Posted by mixja View Post
Just saw these from Turner (http://www.turnermotorsport.com/html..._ID=TEN9046MTP) - I guess these would be ideal to do the primary cat delete - anybody got these installed?



Based on what I read, the power gains with 2ndary cat delete are minimal so the turner set up is an option since you are willing to cut the midpipe and weld it to the turner straight pipe. The better option is to go with High flow sport cats from Fabspped or Encore and weld it to the rest of the x-pipe. That way, you gain the most since the primary cats are the most restrictive part of the exhaust and keep the stock secondary cats and resonator to keep the noise levels down and won't be smelling or inhaling exhaust fumes.



Another option, albeit more noisy, would be to get the high flow cats along with the resonated x-pipe. It will be noisier due to lack of secondary cats but I don't know how loud it is going to be. The advantage would be a little more power and no cutting of the stock midpipe.
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      09-02-2009, 04:26 PM   #15
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Quote:
Originally Posted by NavM3 View Post
Based on what I read, the power gains with 2ndary cat delete are minimal so the turner set up is an option since you are willing to cut the midpipe and weld it to the turner straight pipe. The better option is to go with High flow sport cats from Fabspped or Encore and weld it to the rest of the x-pipe. That way, you gain the most since the primary cats are the most restrictive part of the exhaust and keep the stock secondary cats and resonator to keep the noise levels down and won't be smelling or inhaling exhaust fumes.
With the Primary Cat delete, you still have the Secondary Cats in place, so I'm assuming fumes won't be an issue (also where I live we don't have emissions checks so that isn't an issue for me). So I don't really see the point of replacing the primary cats with high flow cats in my situation, if you are going to keep the secondary cats.

The only potential reason for replacing with high flow primary cats would be that having a straight through pipe might upset your backpressure balance too much causing the low RPM torque dip you see with full aftermarket systems - but I'm picking the remainder of the OEM system will keep a sufficient amount of backpressure to avoid this issue (and hopefully still be able to flow enough to maximise power at high RPMs)


Quote:
Originally Posted by NavM3 View Post
Another option, albeit more noisy, would be to get the high flow cats along with the resonated x-pipe. It will be noisier due to lack of secondary cats but I don't know how loud it is going to be. The advantage would be a little more power and no cutting of the stock midpipe.
Not really an option for me, want as close to stock as possible (just want performance gains )
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      09-02-2009, 08:27 PM   #16
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Quote:
Originally Posted by NavM3 View Post
Based on what I read, the power gains with 2ndary cat delete are minimal so the turner set up is an option since you are willing to cut the midpipe and weld it to the turner straight pipe. The better option is to go with High flow sport cats from Fabspped or Encore and weld it to the rest of the x-pipe. That way, you gain the most since the primary cats are the most restrictive part of the exhaust and keep the stock secondary cats and resonator to keep the noise levels down and won't be smelling or inhaling exhaust fumes.
My reading of the product is you only cut - you don't need to weld because it provides clamps that seal the system.
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