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Highflow cats and codes plus shorty headers

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Old 04-27-2016, 03:54 AM
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corvettenoob1
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Default Highflow cats and codes plus shorty headers

So im thinking my next mod was going to install shorty headers because of emissions and high flow cats just to give the exhaust alittle louder note. What cats can I get that dont ever throw codes?

Now keep in mind these 3 things:

!. I need shorties for emissions
2. Want to remove the restricted stock to make slightly more power and more noise
3. Im on a budget so I cant get LTs

What is the sound difference between the two if I get one or the other? I dont want to be asloud as long tubes, but I want to hear my exhaust over loud music or atleast equal in sound.
Old 04-27-2016, 07:14 AM
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warren s
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You may want to save your money……

“Shorty” headers are just slightly better exhaust manifolds. Better cats would only make a difference if there are other engine mods that can benefit from the extra flow potential. Neither of these two will make much of a difference at all sound wise. (or performance wise)
Old 04-27-2016, 08:40 AM
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Gordy M
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Unless you have a high mileage Corvette, keep the stock system. You already have high flow cats and any change will net you about 1hp. If you want it louder get a different exhaust (mufflers) system commonly know as "cat back" exhaust. If you are looking for HP, then a good street tune will get you what your looking for at minimal cost. When looking for a tuner make sure they are going to improve your low and mid rpm acceleration, removing the DBW lag, etc--we have several sponsors like COW who offer these services.
Old 04-27-2016, 08:42 AM
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grantv
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I think you're going to spend a fair chunk of change and be a bit disappointed. The factory manifolds are quite light and flow well, the cats are also pretty decent. You won't see a very appreciable power or sound increase.
If you want more noise look at the mufflers (but don't expect a power gain).
Old 04-27-2016, 11:18 AM
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SuperTom
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I have shorties only because I got them cheap used ~$125. It does a little more volume to the exhaust. And I disagree with the poster above going from the heavy iron manifolds to the thinner stainless was half as light. Small downside for me was with the thinner manifolds some of the bad engine sounds are louder I have a case of lifter tick or piston slap. I really wouldn't fork out the cash unless you can get them used at a good price.
Old 04-27-2016, 01:01 PM
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corvettenoob1
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Well the only way Im getting new exhaust Is if someone buys my tinted targa top and my borla stingers. I know they will sit for another month or so. Ive had stuff sit for a year amd ever get bought.

People will have posts like trade for a quieter exhaust,but arent real serious.
Old 04-27-2016, 01:39 PM
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alxltd1
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Originally Posted by SuperTom
I have shorties only because I got them cheap used ~$125. It does a little more volume to the exhaust. And I disagree with the poster above going from the heavy iron manifolds to the thinner stainless was half as light. Small downside for me was with the thinner manifolds some of the bad engine sounds are louder I have a case of lifter tick or piston slap. I really wouldn't fork out the cash unless you can get them used at a good price.
My understanding is that All 2001's and forward (C5's and Z06's) used the same manifolds, they are cast iron with a heat shield over the top of them. The 1999 through 2000 LS1's used twin wall stainless steel manifolds that look more like tubing. Not sure there was a better flow from one to the other.

The OP has a an 04 so he should have the cast iron manifolds. Your profile says your coupe is a 99 so it should have had the twin wall stainless steel manifolds as stock. Was that not the case?
Old 04-27-2016, 04:18 PM
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SuperTom
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Originally Posted by alxltd1
My understanding is that All 2001's and forward (C5's and Z06's) used the same manifolds, they are cast iron with a heat shield over the top of them. The 1999 through 2000 LS1's used twin wall stainless steel manifolds that look more like tubing. Not sure there was a better flow from one to the other.

The OP has a an 04 so he should have the cast iron manifolds. Your profile says your coupe is a 99 so it should have had the twin wall stainless steel manifolds as stock. Was that not the case?
I don't know they looked thick to me and were much heavier than the headers I put.

Last edited by SuperTom; 04-27-2016 at 04:20 PM.
Old 04-27-2016, 09:03 PM
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grantv
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Originally Posted by alxltd1
My understanding is that All 2001's and forward (C5's and Z06's) used the same manifolds, they are cast iron with a heat shield over the top of them. The 1999 through 2000 LS1's used twin wall stainless steel manifolds that look more like tubing. Not sure there was a better flow from one to the other.

The OP has a an 04 so he should have the cast iron manifolds. Your profile says your coupe is a 99 so it should have had the twin wall stainless steel manifolds as stock. Was that not the case?
From what I've read, the cast manifolds gained just over 4# but also increased power by about 4HP.
LT's are about 15# loss with obviously much better HP gains.
Old 04-28-2016, 02:00 AM
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corvettenoob1
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I just need something that will increase the volume enough where I can enjoy the exhaust aswell as music.

LT's are out of the question because of emission requirements despite I didnt get a visual at one place.
Old 04-28-2016, 01:32 PM
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You must live in the Peoples Republic of Kalifornia.....

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Old 04-28-2016, 01:41 PM
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I have Kooks LT's with their high flow cats. The reality of it is unless you have other supporting mods like cam, heads, etc., keep your exhaust manifolds. If sound is all you're after - get an exhaust that you like with an X-pipe to eliminate the motorboat sound. Headers will enhance the sound of a exhaust system, but when the C.A.R.B. legality issue comes into play, shorty headers just don't make enough difference either performance wise or sound wise to justify the expense.

Personally - I'd look into the Corsa Extreme with an X-pipe for a throaty idle, great sound at WOT and absolutely zero drone at cruise.
Old 04-28-2016, 02:05 PM
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SuperTom
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Again they are worth it at a used price <$200 shipped. Otherwise skip
Old 04-28-2016, 03:08 PM
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corvettenoob1
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I never notice drone because It never bothered me. Ive had straight piped NA's to turbos and it never bothered me since owning cars like that.
Old 04-30-2016, 06:08 AM
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Not4spd
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I have Shorty's, straight pipes (removed H), and cutouts on mine. Just the right setup sound wise with lots of compliaments.

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