anybody ever put headers that go from 3 inch to factory axle backs (2.5)

[Islandcat]

Thinking about pulling the trigger on a set of kooks today, but I don't really want to buy a 3 inch system because I don't want to buy a 3 inch cat back system. I already have an offroad h pipe and like the way it sounds with the stock mufflers. Its not too loud and sounds good.

So I am thinking of just getting the 3 inch that goes to 2.5 inch (factory connect) . I am wondering what kind of power loss if any there will be by going this route. Their doesn't seem to be much information regarding this on the internet. I called kooks and they said getting the factory connect option doesn't really hurt performance at all. Most people go with the 2.5 inch cause it sounds better. ( that's what they told me). Anyway, my setup has a Trinity TVS, 67MM TB, 123 CAI, and 72lb injectors. Anybody have experience in this situation? I am fine if I lose 5-10 rwhp, but if it costs 20+ then I will have to reevaluate the situation.

 

[12boss302]

With that setup, I think your best bet would be to run a full 3" system so that you flow consistently. It's not too much of a bottleneck honestly but if you've got the capability then might as well use it ya know? 3" is going to be louder than the 2.5" yes, but you could always just get the 3" X and 3" O/A pipes and keep your stock mufflers. But if you're going to end up getting an exhaust down the road eventually, you should just do the 3" out the gates.

 

[Willie]

Sleek98 posted this recently >> Pretty good video >>

 

[Islandcat]

only thing I don't like about this video is they show that it runs rich with 2.5, and they blame it on the carburetor signal being distorted by long exhaust, or whatever they exactly said. Then they put the 3 inch on and they show us the piece they were putting in to monitor the air fuel ratio, and then after the test they never speak another word about it. What did the 3 inch do? Did it run rich like the 2.5, or was it pretty spot on?

I am not saying it would have closed the gap much if any at all, but I would have liked to see them tinker with the 2.5 setup some more and get it running dead on like they had it for the open exhaust.

But I am no mechanic so maybe they didn't need to do any of that and it run what it run and that is that! lol

 

[Stan Bartol]

My 2007 makes 830 RWHP with ARH headers stock rear pipes/ mufflers

 

[Willie]

Yes but would it make 850 rwhp with a full 3-inch system?

 

[1 Alibi 2]

2011
1 3/4" Kooks, " green " catted X pipe, stock mufflers.
2014
1 7/8" Kooks, " green " catted X pipe, stock mufflers.

 

[Islandcat]

I talked to my tuner last night. He just so happened to install a kooks header that goes to factory connect last week. He said it flowed really well and if I wanted to go that route then he was ok with it. Anyway I ordered the 2.5 connect off-road hpipe and 1 7/8 headers last night. I will see what happens but I am excited now ! Lol