I have a 440 stroker w/ TFS 235s on my 04 Z06.

I am currently making 550/520 rwhp/rwtq through 1 3/4 LGs and stock Ti mufflers.

I need to know which headers I should get (assuming 1 7/8). Should I go bigger?

Also, I am going to get some weld on dumps, but the car must have highflow cats and keep the stock tis. Can the dumps go before the cats? and does it really matter that much that the dumps may be placed after the cats?

Thanks,

Rich

 

If the dumps are before the cats, the car will fail inspection if you are trying to keep a legal appearance.

FWIW, I don't think I've seen any of the header makers post that their 1 7/8" significantly outperforms the LG 1 3/4" on a C6 Z06. This may not provide the best return for the money.

Do you have a fairly mild cam?

 

thanks. from what I have read, the 1 7/8 do not significantly outperform the LGs on a atock ls7, but I have a 440 making 550 rw through the factory mufflers.

The cam is fairly big (250s).

So will 1 7/8 add a benefit?

I want the dumps before the cats for max power, but I want cats for cruising around so I dont get lung cancer.

Not worried about inspection.

 

Even on moderately modified LS7's I haven't seen anyone make the switch and gain more than 10 or so HP. Doesn't mean that you won't, only that I missed that post as variation among cammed cars can be big.

 

Thanks. Looks like I stick with my LGs then and get the air tube which broke off rewelded. (didn't mention it before).

Then I will do some dumps to see if I can get the power up by 20 rwhp or so.

Anyone else with an opinion?

 

I would think with your larger engine and cam, that the 1.75"s may be choking it a little bit, and that a 1.875" would pick up some up some on the top end. After you put the dumps on it'll probably be more obvious if the headers are a restriction or not. As far as where to put the dumps, most seem to place them just before the catback on a C5. Might be an issue with lack of backpressure if you put them before the cats that far up the exhaust. All that said, that'd just be my questions if in your shoes.

 

I'm surprised with a 440ci that 1 7/8" headers wouldn't yield more of an increase in HP over the 1 3/4".

 

I doubt you'd see an increase worth the money, but what is your goal? The car has to be pretty fast as is. I think loosing your cats is the best HP gain to be had for the dollar, but you will definately smell exhaust.
There's a point of diminishing returns, and I think you're there. There are no big gains from 550, only small ones that do add up, but take a toll on your wallet.
I'm running 1 7/8" stepped to 2".

 

Roger.

My airtube broke on my LG and I need to get it rewelded. Since I am in an apt complex right now I may have to pay for labor to have the header removed. So I figured while it was out I would swap the headers for bigger headers if the gain was sizable enough. Maybe I'll just have some dumps welded on after the x-pipe and call it quits.

PS thanks for your help thus far.

 

My 408 is giving me 524/501 through 1 3/4 Jet Hots, I also have been debating on whether to go to 1 7/8, the 1 7/8 have a 15% greater cross section. If I only get ~10 more hp I don't know if $1,000 is worth it.