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Discussion Starter #1
As the title shows.

The car, as expected, reacts very well to exhaust.

Baseline - 2008 G8 GT Premium package (18" wheels) - Stock
After - 2008 G8 GT Premium package (18" wheels) - 2.5" Magnaflow cat-back exhaust

 

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Do you have any video clips of the before & after?
 

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Discussion Starter #5
Actually after seeing pictures of what the stock mufflers looked like inside, I was expecting more of a gain.
Take a close look at the dyno chart ...

It could have easily reported some glorified 25 hp gains if testing perameters were allowed to slip. Most dyno charts of similar conditions on a dyno jet have reported 295-305 rwhp on a stock G8. I also observed this and have a dyno chart that reported a low 300 rwhp number.

The problem with using this number and then then comparing the peak numbers after development is heat exposure. I will elaborate. Few performance shop / dyno shops worry about normalizing conditions before making passes. Typically for those who want to go and make a few passes for a $100 the shop straps you down and makes three passes with limited cool down. If you are lucky you get an A/F read out but rarely do you see OBDII scans to verify conditions are similar. In a research and development atmosphere it is essential to control as many variables as possible. Few have the luxury to spend several hours on the dyno with a dedicated dyno tech and the proper monitoring equipment. Often times a car is run hot or as delivered for the before dyno and then parts are made, the vehicle sits for hours or days and then and after run is made in cooler ambient (IAT)and engine temp (ECT) conditions. For those familiar with GM calibraions on the G8 or even the GTO for that matter, you know there are a good deal of countermeasures built in for combating detonation. IAT and ECT play a huge roll in total timing achieved and fueling.

All that considered, when the car is allowed to cool to the same conditions it would be tested in for the after dyno and the vehicle can be properly brought to operating temp under controlled conditions with the use of OBD II monitoring, more consistent and accurate numbers can be had. I could surely report 20+ hp gains but while the dyno chart might show it, is it accurate? As you can see, the test vehicle in stock form produced 313 rwhp when all testing conditions were kept in check.

The stock exhuast does well to serve its purpose as an OEM exhaust but you have to think if there were 25+ hp in an emissions legal cat-back that could satisfy legal noise levels for a 360 hp vehicle, did the OEM really do their homework? As much as you might want to belive not ... OEM engineers really do a great deal more than what we give hem credit for.
 

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This is just exhaust changes with no mods to the tune? If so, that is pretty damn good!
 

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Discussion Starter #7 (Edited)
This is just exhaust changes with no mods to the tune? If so, that is pretty damn good!
Just exhaust ... Tune will follow after all the development has been completed.

Here is the underbody shot of the completed 2.5" system:


Here is a rear shot of the tips:


Close up:
 

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just a question i think i maid a bobo i put a 2.25 x pipe in there did i put too small of an x pipe in there? thanx guys in advance
 

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Just exhaust ... Tune will follow after all the development has been completed.

Here is the underbody shot of the completed 2.5" system:


Here is a rear shot of the tips:


Close up:

oxidizr: Has a tune been developed that's been matched up with the Magnaflow Cat Back system? If so, and you've got the numbers, could you post them?

These pictures are great!

*** One other question, will this Magnaflow cat back system work with Kooks Long Tube Headers?


:)

...
 

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Discussion Starter #16
oxidizr: Has a tune been developed that's been matched up with the Magnaflow Cat Back system? If so, and you've got the numbers, could you post them?

These pictures are great!

*** One other question, will this Magnaflow cat back system work with Kooks Long Tube Headers?


:)

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I have a calibration I mapped in HPTuners. There is really nothing "special" about the tune as it compensated for the better exhaust flow and corrected typical fueling issues found with stock programs. Should be a typical log and tune session or a few hours on the dyno.
 

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Does any sponsor or company have these Magnaflow 2.5 inch cat-back systems in stock? I could only find the system at Summit Racing.

--Mike
 

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Does any sponsor or company have these Magnaflow 2.5 inch cat-back systems in stock? I could only find the system at Summit Racing.

--Mike
I got a this cat-back system due to arrive today from hottexhaust.com. You can try them to see if they have any stock. It was about a 2 week wait for them to ship mine, but you never know. They have a discount code on here somewhere if you search for it.
 

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fordtruck8

coupon code
 
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