flowmaster
"Supporting Systems A true high-performance engine relies on outstanding support systems and thoughtful engineering that touches every detail. The Lexus IS F's unique stacked quad diffusers, for example, make more than a visual statement. They play an important role in a high-performance exhaust system by reducing backpressure. The stainless steel exhaust system starts with tubular exhaust manifolds and integrated catalysts. Next come dual 2.4-inch diameter front pipes that are joined before a pre-muffler and 2.7-inch single center pipe, after which the system splits into two 2.1-inch pipes and enters dual 16.8-liter mufflers."
Lou
Lexus Champion
Joined: Feb 2001
Posts: 3,124
Likes: 32
From: Texas
According to Lexus the dimensions are:
"Supporting Systems A true high-performance engine relies on outstanding support systems and thoughtful engineering that touches every detail. The Lexus IS F's unique stacked quad diffusers, for example, make more than a visual statement. They play an important role in a high-performance exhaust system by reducing backpressure. The stainless steel exhaust system starts with tubular exhaust manifolds and integrated catalysts. Next come dual 2.4-inch diameter front pipes that are joined before a pre-muffler and 2.7-inch single center pipe, after which the system splits into two 2.1-inch pipes and enters dual 16.8-liter mufflers."
Lou
"Supporting Systems A true high-performance engine relies on outstanding support systems and thoughtful engineering that touches every detail. The Lexus IS F's unique stacked quad diffusers, for example, make more than a visual statement. They play an important role in a high-performance exhaust system by reducing backpressure. The stainless steel exhaust system starts with tubular exhaust manifolds and integrated catalysts. Next come dual 2.4-inch diameter front pipes that are joined before a pre-muffler and 2.7-inch single center pipe, after which the system splits into two 2.1-inch pipes and enters dual 16.8-liter mufflers."
Lou
Anyway, this gives:
Duals out of the cats at 60mm/2.4"
Single center pipe at 70mm/2.7"
Duals to mufflers at 55mm/2.1"
Would love to do a backpressure test at various points. Any Houston owners interested in some testing?
Lexus Champion
Joined: Jun 2007
Posts: 2,148
Likes: 0
From: Aventura, Florida
And here are the vids
Sound clip 1- http://videos.streetfire.net/video/I...ust_642011.htm
Sound clip 2- http://videos.streetfire.net/video/I...t-2_642015.htm
In car- http://videos.streetfire.net/video/I...Car_642013.htm
Sound clip 1- http://videos.streetfire.net/video/I...ust_642011.htm
Sound clip 2- http://videos.streetfire.net/video/I...t-2_642015.htm
In car- http://videos.streetfire.net/video/I...Car_642013.htm
And here are the vids
Sound clip 1- http://videos.streetfire.net/video/I...ust_642011.htm
Sound clip 2- http://videos.streetfire.net/video/I...t-2_642015.htm
In car- http://videos.streetfire.net/video/I...Car_642013.htm
Sound clip 1- http://videos.streetfire.net/video/I...ust_642011.htm
Sound clip 2- http://videos.streetfire.net/video/I...t-2_642015.htm
In car- http://videos.streetfire.net/video/I...Car_642013.htm
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Lexus Champion
Joined: Jun 2007
Posts: 2,148
Likes: 0
From: Aventura, Florida
I want to dyno the car but i probably wont get around to it until im done with the mods that i want. I plan on an intake and MHP tune within the next month or so. After that comes my Bday present
Lexus Fanatic
iTrader: (10)
Joined: Nov 2004
Posts: 13,441
Likes: 1,076
From: Under an IS F since 2008
I had Flowmasters on my 88' Stang... V8 American Muscle.. 
For the question regarding the secondary cats delete, not too big of a deal since the MAIN cats are still on the manifold.. But with out mufflers, it probably wont pass smog via the sniffer or visually.
Also, the exhaust flow right after the resonator is still restricted by the flat crushed piping.
In my honest opinion, modifying the oem exhaust piping or cutting it up can be costly down the road...
Technically, any exhaust modification made to the OEM Exhaust by removing parts of it, is "illegal".. Replacing it entirely with a modified system is also "illegal"...
Thats why lots of performance exhaust components are sold with the "For Off Road Use Only" disclaimer.
MRxSLAYx, nice work on the exhaust modification.. It sounds pretty mean!!
Hopefully, you got some before dyno runs in??
With out that, you really won't have a clear comparison as to what gains you may have achieved with your current mod or future mods.
Joe Z
For the question regarding the secondary cats delete, not too big of a deal since the MAIN cats are still on the manifold.. But with out mufflers, it probably wont pass smog via the sniffer or visually.
Also, the exhaust flow right after the resonator is still restricted by the flat crushed piping.
In my honest opinion, modifying the oem exhaust piping or cutting it up can be costly down the road...
Technically, any exhaust modification made to the OEM Exhaust by removing parts of it, is "illegal".. Replacing it entirely with a modified system is also "illegal"...
Thats why lots of performance exhaust components are sold with the "For Off Road Use Only" disclaimer.
MRxSLAYx, nice work on the exhaust modification.. It sounds pretty mean!!
Hopefully, you got some before dyno runs in??
With out that, you really won't have a clear comparison as to what gains you may have achieved with your current mod or future mods.
Joe Z
Yes, but stock came with four cats, the second two only are removed in this application. The primary cats are still there. But, yes, to remove any cat is illegal. But, I also have my secondaries removed and everyone with the JoeZ or SRT exhaust also has them removed.
Lou
Lou