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Discussion Starter #1
Just got a promotion, now I can finally do some major modding. :jammin:

I want to buy Kooks 1 7/8" Headers, but it has been suggested on this forum to go with 1 3/4" for stock displacement motors. What would the negative effects be if I used 1 7/8" ? Eventually I plan to do some major motor work that would warrant 1 7/8" headers, and I'd like to avoid buying two sets of headers. So, if using the 1 7/8" now only minimally affects performance as opposed to 1 3/4", I wouldn't mind. Any Input is appreciated.
 

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Very minimum

I have seen stock cube motors run both the 1 3/4" & 1 7/8". You MIGHT(maybe) lose about 3-5 lbs. torque midrange torque. Someone just did the 1 7/8" on a stock motor, no problem after the 1 3/4", no noticable difference on the dyno. I was a little surprised. Maybe be better tuning. Who knows.

I would run the random cats and keep your titanium Z06 exhaust(this reduces the 3" pipes down to 2.5", good for torque) and run with the 1 7/8" headers particularly if there is more cid, nitrous or a blower coming in the future.
 

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You will lose some Torque below 4000 RPM, which IMO will never gain it back as long as you stay with stock CID. If you plan to go to a Stroker motor then by all means step up to 1 7/8. I can't think of one advantage of the 1 7/8 over the 1 3/4 on Stock CID regardless of future mods. :cheers:


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You will loose torque if you change the headers to 1-7/8 without any other mods. Stick with 1-3/4 without any other mods...Kooks makes great headers as I have 1-7/8 on the aft of my 427
 

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Discussion Starter #5
ScDFACHE said:
You will loose torque if you change the headers to 1-7/8 without any other mods. Stick with 1-3/4 without any other mods...Kooks makes great headers as I have 1-7/8 on the aft of my 427
Are you saying I will lose torque by replacing the stock manifolds with 1 7/8" headers? Or do you mean I would gain less torque with 1 7/8" than I would from 1 3/4" right now. And how much of a loss are we talking about? I could live with gaining around 5 ft./lbs. of torque less than I would with the 1 3/4" at the moment, since I have plans for larger displacement in the future.
 

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A&A did a dyno run, before and after the 1-7/8" Kooks install, and I gained 20RWHP & 20RWTQ. There was no drop at all and the gain was across the whole RPM range. I also had the Kooks X-pipe done at the same time. I went this route because I knew what I was going to put a blower on it.
 

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Discussion Starter #8
rocman said:
I gained 20RWHP & 20RWTQ.
Nice numbers! My car is almost stock, but I do have the vortex rammer and air bridge, which brings in a ton of air at speeds over 100mph. I think I might get some great power at high speeds by adding the headers and getting rid of all that intake more efficiently.

Also, I plan on keeping my stock cats, and I also want to keep the stock h-pipe because I like the sound it makes. I have an x-pipe lying around, should I have it welded on after the cats and before the h-pipe, or would i have to remove the h-pipe for there to be any difference?
 

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Your car will make more power if your X pipe is on before the cats. One of the only headers that is made that let you keep your stock cats is Stainless Steel Works and they only come in 1 3/4.
:z:
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Rockman, you may have lost one whole hp and one whole torque. Woo Woo. However, I am sure your free'r flowing exhaust removes more heat from the engine compartment when on the gas at speed. Ten degee's less underhood temp equals about seven h.p. on a 346, not to mention less wear and possiblity of detonation.

The TRACK temperatures on my 11.0 compression 430 cid, usually run between 185-195(water) vs. guys I know running 210-235(water temp). Cool air in, cool intake & manifold, hot cylinder temps, hot air out, cool engine comparment, cool oil & water is the way to go. Heat soak kills h.p. in the real world.
:D
 

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Discussion Starter #11
IT L GO said:
One of the only headers that is made that let you keep your stock cats is Stainless Steel Works and they only come in 1 3/4.
On tbyrne's website, the kooks headers are listed with weld on collectors. There is also a separate part:

" 3" Stock Cat Hook-ups (Comes With 1 Pair Of 3" Flared Tubes and Flanges)"

Am I correct in thinking I can use these headers with stock cats?
 

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will82 said:
Am I correct in thinking I can use these headers with stock cats?

Nope :crazy:
 

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Discussion Starter #13
IT L GO said:
Nope :crazy:
Thanks for the heads up. I would have been ticked off! I guess I'll have to shell out for the custom x-pipe with cats. Since we live in Florida I suppose I could go without cats, but I've heard this can produce an unpleasant smell. Is this so? And how would no cats change the sound as opposed to high-flo cats?
 

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No cats are louder than cats by quite a bit. Supermaxx makes a nice set of longtube Headers with cats, Xpipe etc for around 1300.00 shipped.
:z:
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Discussion Starter #15
IT L GO said:
No cats are louder than cats by quite a bit. Supermaxx makes a nice set of longtube Headers with cats, Xpipe etc for around 1300.00 shipped.
:z:
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$1,300 with shipping included!?! That sounds good to me! Who has this deal? (p.m. me if it's not a forum vendor). This is the only system other than LG that has 32" primaries, right? How much more power does that make vs. regular length long tubes? Enough to help counter the loss from not having 1 7/8" primaries when I get more c.i.d. ?
 

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will82 said:
$1,300 with shipping included!?! That sounds good to me! Who has this deal? (p.m. me if it's not a forum vendor). This is the only system other than LG that has 32" primaries, right? How much more power does that make vs. regular length long tubes? Enough to help counter the loss from not having 1 7/8" primaries when I get more c.i.d. ?
I send you a PM :z:

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You could select a step header such as Breathless makes. It goes from 1 3/4 to 1 7/8. They create a great deal of usable torque with a very flat curve.

Don
 

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will82 said:
Thanks for the heads up. I would have been ticked off! I guess I'll have to shell out for the custom x-pipe with cats. Since we live in Florida I suppose I could go without cats, but I've heard this can produce an unpleasant smell. Is this so? And how would no cats change the sound as opposed to high-flo cats?

If you go without cats, better invest in a gas mask or keep the windows up. :roll: The smell does more than clean out your sinus... :yeadog:

Bob :D
 
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