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Header and Hi Flow cat question

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Currently I am running the stock manifolds along with an off road H pipe into the stainless works exhaust. My question is will I gain by adding headers but changing out the off road H pipe with a hi flow catted H? I think my county is about ready to start checking for cats.I understand I will have to re-tune. Also is long or short tube the better option?

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If they look for cats then they will look for headders. If they go in your GT500 then they are a pain to install. Headders aren't smog legel ether.

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Currently I am running the stock manifolds along with an off road H pipe into the stainless works exhaust. My question is will I gain by adding headers but changing out the off road H pipe with a hi flow catted H? I think my county is about ready to start checking for cats.I understand I will have to re-tune. Also is long or short tube the better option?

 

In my opinion, the safest way to "possibly" get through the initial "visual emissions inspection" is to have shorty's installed and when it comes to inspection time, throw the oem H back in place and the system will appear oem to the visual from the bottom side, which is where they look first. Getting through the visual inspection is the big deal, when they see "aftermarket" exhaust parts anywhere ahead of the catback when they initially look under the car, the flags go up and the bells and whistles go off, then they start sniffing around a little more.

 

The problem is, FRPP no longer makes the shorty headers for the 2007-2014 GT500 and the JBA shorty that has been talked about on a few forums is not available yet. JBA says their shorty's will be CARB approved.........maybe that is why it is taking longer to get them to the market place.

 

My FRPP shorty's are not CARB approved, and thankfully, for now I do not have emissions testing/inspection in my area.

 

My thought is..............If you take off the oem rusty cast iron logs and replace them with a set of nice shorty's along with a nice large mandrel bent system (I have Shelby/JBA 3"), it will flow fine. Long tubes show better hp gains in tests that have been conducted in the past, but most owners who installed the shorty's were still running the choked down oem 2.5" exhaust that comes on the earlier cars. The 2011-up 2.75" is better, but still not mandrel bent, so it chokes in the bends around the axle.

 

BTW - The outlet size on the oem cast iron logs is 2", so that is a flow issue immediately, without looking anywhere else.

 

 

 

R

Edited by Robert M
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I've decided to go all Stainless works from long tubes, OR H pipe and retro straight through mufflers already installed. Adding upper and lower pulleys as well as steeda adjustable tensioner up top.

Also added Keene Bell Boost a pump. Top it off with BMR front and rear sway's and Watts link. I already had all the rest of suspension repleced with BMR except went with Ford Racing springs.

Cant wait to see the dyno results and feel the handling difference.

 

As always thanks for your input.

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