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Discussion Starter · #1 ·
I liked the Borla ATAK before the headers went on. It was a touch raspy at high rpms, but still sounded really nice.

I don't like it now. Much to raspy at WOT and will simply alert every cop within 20 miles. I can't go WOT, it's just to loud.

So... I ordered some Kooks Mid-Pipes for a 6.1 /6.4 SRT and then ordered Zoomers for a 6.1 /6.4

The mids will bolt right up to my long tubes and the zoomers should fit fine. A full 3" exhaust is overkill for my 5.7L, but I now have more power than a stock 6.1L, so it shouldn't hurt anything.

The 3" piping will really deepen the exhaust note and I know Zoomers isn't nearly as loud as the ATAK.

Zoomers appears to have no rasp and I ordered the Zoomer tips to eliminate any flutter.

Hope it works out okay. I like loud exhaust, but not Nascar loud.
 

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Discussion Starter · #3 ·
Yes, I made around 320 rwhp and 350 ft lbs on a dynocom load based dyno.

This was done in 86* weather with 3* timing being pulled. When I get the tune dialed in and with cooler weather, I would likely make 375-380 rwhp and 400 ft lbs on a dynojet.

Stock 6.1L's seem to dyno around 360-365 rwhp and 370 ft lbs stock on a dynojet.

My comment was only to reference that my engine is similar in horsepower to a 6.1L and should exceed the torque output by a fair margin.

This allowed me to justify using a exhaust setup for a 6.1L. The 6.1L does have slightly larger displacement, but this should prove negligible.

A little low end loss will not hurt me due my 6 speed and 3.92 gears.
 

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3" is a bit too wide for an R/T. Even Frank at Zoomers said that the 2.5" was too wide so they ended up going 2.25" which helped restore some torque and help exhaust scavenging.

You're right, Zoomers is very deep, and smooth. Best of all there is no drone.
 

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Discussion Starter · #5 · (Edited)
I will be doing a retune and dyno soon. It will be interesting to see the results with the 3" piping of the Zoomers.

The Kooks mids are 3" on a 5.7L or 6.1 / 6.4L. The only difference is the outlet sizing (2.5" vs 2.75")

Maybe Zoomers original development was on the older 5.7L's. With the typical bolt on's, the 5.7L VVT motors are equal or exceed the 6.1L concerning output, especially in torque.

Hard for me to believe that a modded 5.7L VVT would only support 2.25" pipe, while the 6.1L supports 3".

I think that is why Dodge stepped up to 2.5" piping on the VVT 6 speed R/T's.
 

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The Atak has specially designed mufflers that are setup for the stock cats and manifolds. When you put headers and high flow cats, it will change the sound a bit...and in an undesirable way. The S-type is best for long tubes...but maybe a bit quiet without.
 
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