Frank Talk About Headers Requested

Right now, I am leaning against considering a header install on my '17 GT350, but I would like feedback from members who have already done this. In retrospect, are you glad you did this mod? If not, why not? If yes, what were your verifiable power gains? I am particularly interested in those that did headers with high flow cats that plug into the balance of the car's stock exhaust system.

Despite a number of threads here on that topic, I don't think all the information I am looking for is clearly laid out in any of them. I am not adverse to modding the car "within reason" having already done intake and a custom tune with pretty good results. So clearly, I am willing to do a certain level of mods. And I have found through my own experience, that these cars really respond to raising the octane by adding 5 or 6 gallons of legal 100 octane to the tank. I like E85, but too much of a pain since I live in Florida and it is so hydroscopic.

Here is what I "think I know:"

1. The two most popular Header manufacturers are ARH and Kooks;
2. Both brands offer "high flow cats" and can connect to the balance of the stock exhaust system;
3. Headers for the GT350 are made of significantly thicker gauge SS to help deal with FPC higher levels of vibration;
4. Some people allege that the real gains from header systems (20 or so rwhp?) are mostly the result of them using significantly better flowing cats than stock, as opposed to the majority of results coming from improvement over the factory header system;
5. Installation of headers on our cars is a royal PITA which involves many hours of labor and a shop who is extremely competent to tackle this;
6. This is a very expensive mod (over $3k) due to the cost of the headers, install, and required resultant tuning.

Questions re your specific experience with headers on this car:

1. Would you do it again? Why or why not?
2. Approximate costs of the headers you bought and all related labor and tuning costs? What brand did you choose and why?
3. For those of you who connected headers into your stock system, how much louder was the exhaust? Do you like the sound of the system as opposed to the stock system sound (Which I really like).
4. What were your documented before and after rear wheel h/p and torque numbers? Were these with or without other mods?
5. Did you have your headers thermal coated before installing? I have always done this with any prior cars I had (Corvettes). I used a real, proven ceramic thermal coating - SwainTech with very measureable reductions in heat loss from the pipes.

Thanks in advance for taking the time to respond. I am really interested in member's responses NOT vendor responses. Again, right now, I am thinking more seriously about getting sprung and unsprung rotating mass weight off the car - perhaps equivalent to around 200 lbs. Starting with the wheels, which weight a ridiculous 31 lbs each.


Thanks again..

Great topic and questions.

17RubyShelbyGT350 said:

Here is what I "think I know:"

Questions re your specific experience with headers on this car:

1. Would you do it again? Why or why not?
2. Approximate costs of the headers you bought and all related labor and tuning costs? What brand did you choose and why?
3. For those of you who connected headers into your stock system, how much louder was the exhaust? Do you like the sound of the system as opposed to the stock system sound (Which I really like).
4. What were your documented before and after rear wheel h/p and torque numbers? Were these with or without other mods?
5. Did you have your headers thermal coated before installing? I have always done this with any prior cars I had (Corvettes). I used a real, proven ceramic thermal coating - SwainTech with very measureable reductions in heat loss from the pipes.

Thanks in advance for taking the time to respond. I am really interested in member's responses NOT vendor responses. Again, right now, I am thinking more seriously about getting sprung and unsprung rotating mass weight off the car - perhaps equivalent to around 200 lbs. Starting with the wheels, which weight a ridiculous 31 lbs each.


Thanks again..

Click to expand...

1. Yes

2. Bought the Kooks headers, and Xpipe /NC and it was under 1500. Bought them from Beefcake on a sale. I purchase the Kooks because they had the most research, and info out for the GT350. Also I liked their stepup system for the headers and the GT350. This resulted in more low end TQ.

My labor was not bad, though a bit more than I thought, the work done was top notch and the attention to detail may not have been done from a different shop. The tune was a Flex tune from Lund, with the Ngauge. Great product. My car on the corn is at 525/425.

3.My system has the OEM mufflers. Yes it is louder. by quite a bit. But it sounds GLORIOUS at wot. I'll try to leave a sound of me running a full bolt on Termi at the end of this.

4. As I said I am at 525 on the corn. 505 on 93. I did not get a before and after sadly. But I have done this enough to know the car even on 93 responds better with my tune. On e85 I have zero issues. I'm in Miami btw.

5. No. I have done it in the past, but with the way Kooks were made, actually most new headers, It was advise that coating was not a necessity. Also I will not be hard core tracking so I did not do it. I have made passes at the track though and my temps are well within range.

I would say the headers are def a good mod. Exp if you have a tune. Sure it's pricey, but its worth it IMO. The only reason I would not do it, if I was going to go turbo, which I decided against. The power I make is more than enough on the street, and I do not have to worry about breaking stuff. Having 700/800/900 is cool bragging rights, but really...honestly...were will you use it ??? Trust that I say this because I sold my 700+ 11 Shelby.

Hope this helps.
Link to sound at WOT

[ame]

Sounds awesome Ninjak. Those last two runs were great.

I want headers badly, just don’t feel like the install, or the cost right now due to other projects. That WOT noise can’t be beat as evidenced in [MENTION=6801]Ninjak[/MENTION] video.


I wouldn’t hesitate to go with stainless works either. They all sound great to me. A tune/header/e85 round of mods will give you a very nice extra kick, then if you get lighter wheels like you’re talking...oh man

The sound is pretty insane. Just note though if you do long tubes and even with high flow cats, you will UNEQUIVOCALLY FAIL sound regulation on any autocross (at least SCCA sanctioned) and road course track in the country except on exception days. And that never happens for autocross (again, SCCA).

Do you guys think even with the kooks, high flow cats, and stock muffler with valves closed, the car would still fail a track noise test?

Thanks

Thanks for your responses so far - with a special call out to Ninjak for his detailed response. Please keep the feedback coming!

Nastang87xx - does your warning about noise limits still apply if you plumb the headers with high flow cats through the remainder of the stock exhaust system?

:cheers:

17RubyShelbyGT350 said:

Nastang87xx - does your warning about noise limits still apply if you plumb the headers with high flow cats through the remainder of the stock exhaust system?

:cheers:

Click to expand...

Yes. Seems like you'll hit well into the 105 dB range at 50 - 75 feet. The factory mufflers are still pretty stout, around 95 dB at 50 feet. I have a resonator delete and I got tagged at autocross at 100 - 101. They gave me pass because I'm consistently within 99 - 100 though.

Demonic said:

Do you guys think even with the kooks, high flow cats, and stock muffler with valves closed, the car would still fail a track noise test?

Click to expand...

Well since the valves fly open at 1/3 throttle I think you're kinda screwed. Even if you could force them closed, I don't think it's a good idea. C6 and C7 guys have burned out their NPP actuators by doing this.

What Nastang says.

I am by no means a expert on the track rules and what not, but I will state even with the valves close if you punch it, they auto open. So you will still get the sound. Now after your initial punch, they will close again, but though I do not know how this would effect your system, I would not recommend it.

I did it because I know I will not be at many of these types of events, and PBIR sort of let you slide every now and again. That is where I would be if I do a event.

Having installed headers myself on a 4.6 and Coyote S197s, those cars were a good 10 hours of work. If you do it, my suggestion is spend a few hundred dollars more and get ceramic coated stainless steel headers. Research this. It keeps engine temps much cooler and produces a bit more HP/TQ. I did a temp check on the factory headers vs the ceramic coated JBAs and it was amazing how cooler the headers and engine compartment was. Plus they don't change color like standard SS headers. With a GT350 I would think engine appearance matters as well.

GreenS550 said:

Having installed headers myself on a 4.6 and Coyote S197s, those cars were a good 10 hours of work. If you do it, my suggestion is spend a few hundred dollars more and get ceramic coated stainless steel headers. Research this. It keeps engine temps much cooler and produces a bit more HP/TQ. I did a temp check on the factory headers vs the ceramic coated JBAs and it was amazing how cooler the headers and engine compartment was. Plus they don't change color like standard SS headers. With a GT350 I would think engine appearance matters as well.

Click to expand...

Agreed. If I went the headers route, I would absolutely ceramic coat them - most likely with the Swain Tech white lightening thermal coating. Ain't pretty but it really works...

However, right now I am really put off by the high level of decibel increase that I previously had not considered. I don't want to get kicked out of any track events and I sure do not want problems with the local PD or Sheriff Dept.

GreenS550 said:

Having installed headers myself on a 4.6 and Coyote S197s, those cars were a good 10 hours of work. If you do it, my suggestion is spend a few hundred dollars more and get ceramic coated stainless steel headers. Research this. It keeps engine temps much cooler and produces a bit more HP/TQ. I did a temp check on the factory headers vs the ceramic coated JBAs and it was amazing how cooler the headers and engine compartment was. Plus they don't change color like standard SS headers. With a GT350 I would think engine appearance matters as well.

Click to expand...

Speaking of JBA headers, do you know anyone running JBA headers on GT350’s? I don’t think many folks are running JBAs recently, or they are not posting. Just curios as they don’t advertise HP gains for GT350.

I will say I have heard the full Kooks system on a GT350r...the gentleman came by my office to hear mines. He thought his was to quiet. I will say his was much quieter than my setup. Even at Wot. He had the green cats in his setup.