I drive a 2007 Pontiac G5 GT (2.4l LE5). I'm trying to find a header with a 2.5" collector prefferably with ceramic coating. I'm doing this all at once with a Magnaflow exhaust system.

It seems like the majority of people are going with the CA header/XTC downpipe but I heard that was a 2.25" collector. Also I don't think it's ceramic coated? Any changes on version 2? All I saw was compatability with the 2.2l for SAI...

A lot of people are picking the mid-length ZZP header/downpipe too, but I think that's a 2.89" or 3" collector?

I could really use some help here guys...

 

I just got the ZZP header dp combo on the group buy, and I'm not sure what the collector measurements are, but if you get the combo the dp will definitely bolt up, and if you choose the bolt-in dp option, you can purchase ANY brand 2.5" cat back and it will bolt up. Does that help?

 

You can get 1.5" primaries which turns into a 2.5" collector or 1.75" which turns into a 3" collector but you can get a dp like the person above me said from 3" down to 2.5".

 

if you get the zzp midlength header, the one from the group buy, there's no dp's that will bolt on without cutting except for the dp that comes with it. stock will not work unless you cut it, and weld the connector back on.

zzp offers a shorty that will bolt up, but that's not the one in the group buy.

 

In comparison, I was looking at the CA Header and the primaries are 1.7. That collector size on the ZZP with 1.5 primaries is perfect, but I'm wondering if the primary size is good enough. Should be N/A... I just like room to work with. I guess the ZZP 1.75 with 3" collector can be downsized just using the 2.5" DP?

I just wish the collector on the CA Header was 2.5" because then it would be ideal for what I'm wanting. I can live without the ceramic coating. Not that worried about heatsoaking...

 

Clear Image has a 2.5" collector i believe, its a 4-2-1 as well.

 

So if I went with the ZZP header w/ 1.75 primaries I should be alright just downsizing the 3" collector with the 3" to 2.5" downpipe they offer? Anyone know if that's overkill on a 2.4? I do plan to mod beyond I/H/E and do an injector upgrade eventually...

Edit: Oh, and any opinions going Catless vs. a HFC?

 

Please... not all at once... lol

 

There are plenty of threads stating plenty of opinions on HFC vs catless

My opinion is...wait until you get inspected then slap a catless on there...

 

I know it's all objective, but my real question was whether getting 1.75" primaries with a 3" collector is overkill vs. the smaller ZZP header? I'm sure the majority of the 2.4 community is going one way or the other by now...

 

a 3" collector isn't overkill , but a 3" dp is. Do they offer 1.75" primaries and 2.5" collector?

 

For the ZZP mid length, all of the headers have a 3" collector regardless if you select 1.5" or 1.75" primaries. The downpipe is what changes it to either straight 3" or reduced to 2.5".
The 1.75" primaries are to big for a N/A engine. In fact while I was installing my header today I looked to see if I may need to smooth out the header to the gasket and found it was exactly the same size with the 1.5" primaries.
So the best options for a 2.4 IMO are,

Model
1.5 inch Ceramic coating
Option 1
Magnaflow cat
Option 2
304 stainless downpipe
Option 3
bolt in 2.5 inch downpipe

This is what I own, this is what I would recomend.

 

Man to bad I already have my cobalt addiction shorty and XTC 2.5 high flow cat, or I would have jumed at this deal.

 

Thanks for the input. I'm concerned about losing the scavenging effect on my exhaust with such big primaries. What bothers me is that the CA header HP gains seem pretty solid and they are 1.7" primaries. Are there any dyno ratings for the ZZP?

Did you get the second O2 bung for wideband? If I choose the Magnaflow cat and hook up my secondary O2 can I avoid throwing a CEL?

 

^^Yes I did get the extra bung for the wideband, but have it plugged for now as I have not purchased the guage yet.

If you get the cat and connect the rear O2 sensor, you will not get any CEL's.

 

LoL I got a cel when I put my XTC HFC on. But it was quickly turned off by HPT

 

that exact setup is in my room waiting for spring, I definately think 1.75 is too big. based on my calculations the cross sectional area of the 1.5 is almost identical to the stock manifold, but its a lot smoother and longer primaries and the dp is a lot better so there should be gains throughout the entire rpm range