Kooks exhaust and factory resonator system.

[cmde44]

So I had Kook's long tube headers and x pipe put on my GT350. They sound fantastic, but I think I have an issue with the resonators / performance valve / whatever it's called in the factory mufflers.

I can flip from normal exhaust to performance like before and it has very similar effects to when it was stock. But, when I'm in normal mode and start to get into it, I get the normal, tuned back sound, but it'll just open wide up to performance mode the higher the revs go.

It seems like maybe the new exhaust is kicking the factory actuators out as you get into it hard? Any ideas on this? Thank you!

 

[Ninjak]

I am getting the same setup installed on my GT350. I think I read somewhere or saw in a vid where there is a auto open of the OEM mufflers when you step into it hard. Even if its in normal mode. The same as when in 6th gear, they close.

Do you have a tune as well ?

Btw, how do you like the new setup ? I went with Kooks because after talking to several installers and vendors, many felt like they were one of the better systems for the vehicle.

 

[cmde44]

I am getting the same setup installed on my GT350. I think I read somewhere or saw in a vid where there is a auto open of the OEM mufflers when you step into it hard. Even if its in normal mode. The same as when in 6th gear, they close.

Do you have a tune as well ?

Btw, how do you like the new setup ? I went with Kooks because after talking to several installers and vendors, many felt like they were one of the better systems for the vehicle.

Sorry for the late response. I just got the car back last Wednesday from having a little work on it. I had Kook's long tube headers, Kook's mid pipe with the smaller cats on it, a JLT air intake, and a custom JLT tune.

The shop took a before and after dyno, then sent the diagnostics straight to JLT and they custom made a tune for it. I was actually extremely impressed because they ran four different tunes through it to get the most ideal setup for me. They could have just done one generic one and moved on, but they were seeking the best they could do.

I really wanted more low end torque, I feel that first and second (for normal driving) is just way too weak. Even thought I only got about a 35 hp and torque gain at the rear wheels, they were able to tune the car to get about 90 more torque at 2800 rpm, AND IT MAKES A HUGE DIFFERENCE! They achieved exactly what I wanted, a beast at the low end rpms as well as the top end.

As far as the exhaust. I had two issues, none of which were the products problem. First, like I said, if you get on it in normal exhaust mode, it opens it up to performance sporadically, which is fine, but the normal mode sounds fantastic in different ways that the performance, so I wish it wouldn't do this. The dealer is contacting Kooks to find out more about this. Secondly, when re-installing the factory mufflers, I think the tech didn't have someone holding the mufflers in place, so when he was tightening them down, the muffler itself turn just a few degrees causing the muffler tips to touch the chrome tips, so I get a pretty bad "tingy" vibration from it.

That aside, it does sound good, but performance mode is loud. I mean, really really loud. I think you could get away driving around in performance mode with the stock setup, but I'm pretty sure I'll get a ticket now. Once I get the mufflers straightened out, and the double check everything is installed correctly on the factory dampeners, I'll let you know what my final verdict is.

 

[cmde44]

This is my potato quality video,

 

[Ninjak]

Well my headers showed up yesterday, and I received my Lund Ngauge on Monday. So Oct 12th is my install date at Power by the hour, so It should be interesting what my final results will be

 

[Ninjak]

CMDe44 I have a question for you. Did you install the stock dampeners on your headers or did you leave them off ? The stock ones on my car are welded to the stock exhaust pipes.

 

[cmde44]

CMDe44 I have a question for you. Did you install the stock dampeners on your headers or did you leave them off ? The stock ones on my car are welded to the stock exhaust pipes.

Yes, they re-used all of the stock dampeners. You have to, otherwise the vibration would be awful. I didn't realize how hard of a time they had with the harmonics on this car, was very surprised when I saw the driveshaft had a carrier bearing.

If it's still being worked on, I have one more piece of advice. On the flanges between the x pipe and the headers, there are clips that snap onto the head of the bolts that prevent the bolts themselves from backing out. Great idea, I know they do it on a lot of race cars, but these tabs / locks are loose on bolts and they vibrate so bad you can hear it distinctly from the cab (there's four of these tabs total).

I wanted to just take them off and lock tight the bolts, but instead we fixed the tabs in place to the bolt head with a tiny weld / tack just to keep it in place. It will still function just fine.

 

[Tob]

I didn't realize how hard of a time they had with the harmonics on this car, was very surprised when I saw the driveshaft had a carrier bearing.

A two piece steel driveshaft has been in use since the S197 and the one in the GT350 is almost identical, carrier bearing is essential the same as well. Steel tubing gave Ford the stiffness they were looking for and by cutting the shaft in two Ford was able to see the critical speed numbers they were looking for.

What is different on this car than all other S550's is the use of 12lbs worth of mass dampers bolted to the transmission crossmember/rear of the transmission.

 

[Ninjak]

Hmm well things seems to have changed up. My car has no bolts. The vibration dampeners are pressed in ? But there is no way to remove unless I cut the dampeners off. I am having Power by the Hour do the install and they have ran into the same issue on a 17 R.

Kooks is saying that Ford has change the system on the later 17's. Looks like a cut is going to be needed to make this happen.

 

[Ninjak]

Well to follow up I have everything on. For the headers vibration pucks, they were cut from the brackets on the stock pipes and mounted to the Kooks headers. The reset was simple.

I will say it much louder in open mode, but I am getting use to it. The resonators were remove as kooks x-pipe and mid pipe took up the space. I was thinking of having resonators added back, but I think I will leave it as is. Its not super crazy, I had just gotten use to the stock setup.

The flex tune is nice. The car is driving good. She laid nice power down on the dyno, 505/422. I'm happy.

 

[cmde44]

I'm still not sold on keeping the factory mufflers. I ordered the Kook's mufflers that go with the exhaust setup. I'll try to get some quality video of the sounds before and after of the exhaust. I'm going to lose my dual tone capability, but it sounds wicked. They also seem to get another 9-10 rwhp with the mufflers.

I keep seeing everyone's high dyno results and I feel like something is off with mine. Headers, x-pipe, intake, and tune took me from 446 oem to 477 after. Could ambient temperature and the engine not being warmed up enough account for some discrepancy? It was 103° and I'm not sure how warmed up the car was before the first pull.

 

[Ninjak]

Hmmm...I spoke with a guy who did this, has a R. He brought it buy my office, and though yes he does has the catted system, It was quiet, much more quiet. His rev up sounded just slightly above quiet mode stock. Now at WOT I thought it sounded fine, now as loud as my setup but I thought it was not bad.

I will say though that the solution from Kooks did not work for him. PbtH told me they had issues. The solve was a bypass harness from Steeda I think ? But I know he eliminated the entire system.

It will be interesting to see how your setup turns out. I like my switch, so I will always keep the OEM mufflers. Also I have had others tell me the car just sounds wicked at WOT and I have gotten used to it now, So I will leave it as is.

Not sure on your dyno numbers....Is it a Mustang dyno or dyno jet ? it does make a difference in the numbers.

 

[cmde44]

I'll be sad to lose the dual tone but I have a wild card. The dealership already said if I'm not happy with the Kook's mufflers, they'll warranty the OEM mufflers for me. They think one of the springs on valve system went out on the driver side muffler. They'll replace them no question.

It was a Dyno Jet. What difference does it make?

 

[Ninjak]

Mustang dyno has more load so will read lower...a lot lower than a dyno jet. Its nice what the dealer is going to do. You have the option.

I'm currently loving my setup. Someone last night when I pulled up stop and asked how fast is that car ???? I said I'm not sure, have not let her off the leash yet... well you should ! Sounding like that I would have found out day one !

Lovin it !

 

[ANGREY]

For you guys who've done this swap, if you don't mind, please post (or PM) with an approximate value of what shops are charging to do the header installation. I'm on the fence with whether I'm going to spend the $ to have a shop do it or rent a lift and do it myself.