Highflow cats and codes plus shorty headers
Thread Starter
Instructor
Joined: Apr 2016
Posts: 152
Likes: 3
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.
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.
Melting Slicks
Joined: Mar 2002
Posts: 2,203
Likes: 63
From: Staten Island NY
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)
“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)
Melting Slicks
Joined: Feb 2001
Posts: 2,804
Likes: 358
From: Northville, MI
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.
Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
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).
If you want more noise look at the mufflers (but don't expect a power gain).
Drifting
Joined: Oct 2008
Posts: 1,595
Likes: 191
From: Wilmington DE
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.
Thread Starter
Instructor
Joined: Apr 2016
Posts: 152
Likes: 3
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.
People will have posts like trade for a quieter exhaust,but arent real serious.
Melting Slicks
Joined: Mar 2009
Posts: 2,300
Likes: 115
From: Odessa FL
St. Jude Donor '10-'12-'13-'14-'15-'16-'17
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.
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?
Drifting
Joined: Oct 2008
Posts: 1,595
Likes: 191
From: Wilmington DE
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?
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?
Last edited by SuperTom; Apr 27, 2016 at 04:20 PM.
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Le Mans Master
Joined: Sep 2014
Posts: 5,278
Likes: 539
From: Kelowna BC
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?
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?
LT's are about 15# loss with obviously much better HP gains.
Thread Starter
Instructor
Joined: Apr 2016
Posts: 152
Likes: 3
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.
LT's are out of the question because of emission requirements despite I didnt get a visual at one place.
Race Director
Joined: Aug 2003
Posts: 16,270
Likes: 30
From: "It's 106 miles to Chicago, we've got a full tank of gas, half a pack of cigarettes, it's dark, and
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-‘18-'19
NCM Sinkhole Donor
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.
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.
