I have a mild 440 with a 557 mopar cam, rpm air gap eddy intake and 10.5 comp....I'm deciding on header size and I looking for performance on the street as well at the track ??? What u guys think ?? Thanks !!

My pump gas 470 makes 700 hp with 2 inch headers on the dyno. I tried a set of 1 3/4 headers to see what would happen and it still made 690 hp.

So I'd suggest using the smaller headers, especially if they fit better.

That's good to know... I've got 1-3/4" on my 451 for both space and cost reasons

Andy, what if anything changed in the torque curve at lower rpms between the two headers?

Who makes the 1-3/4" headers? All I usually see are 1-7/8 or 2"?

Summit has a set for $120? I had them on my tired 440 which ran 12.0's at 113 mph a few weeks ago in my GTX. They fit great!

Ouch!

I just upgraded from 1 3/4 to 1 7/8 to make a touch more power.

Wanted ceramic coated anyways! lol!

with header fitment being the pain that it is, that would be far more important & I would get a set that fits the best (which wont be the 2") whether it be 1&3/4 or 1&7/8

Like Robert said, fitment plays a big part in your choosing the size. With that said, I think tti makes a 1 3/4 size header or they use to. Of course they will cost a lot more then Summit's price of $120.00.

Doug's ceramic 1 7/8"

More gear and stall for mostly track time I would go 1 7/8.Mostly street duty 1 3/4 is fine.Have a good mandrel bent 2.5 exhaust with free flowing mufflers and you will be fine.

I went from 1 3/4 to 1 7/8 on my old 440-6 set up, 588 solid roller, ported Stage VI heads, I picked up not et but did pick up 1mph.

I used to run almost the same combo as I had a 10.5 comp 440 with 906 heads and the MP .557 cam. I used an 850 Holley DP and the Holley Street Dominator intake. I used the Hedman 1-3/4 headers as my buddy gave me them with the car when I bought it. My 63 is all stock body and weighs just over 3700 lbs with me in it and it ran a best of 11.49 at 116 with that combo and the 1-3/4 Hedman headers. Ron

At 440" and a .557 the 1 3/4" will be fine but IMO it's important to remember the collector size will tend to limit the RPM that peak torque will be produced, so if the collector is too small for the compression and cam it will lower the HP trajectory (rate of HP rise per 100 rpm) beyond the peak torque RPM.

It's pretty easy to adapt and weld a larger slip on collector (such as the ones sold by Shoenfeld) to inexpensive headers, Generally, a 3 1/2" collector will likely pick up your HP compared to a 3" even with the same primary tube sizes, all else being equal. That is provided/assuming you will also have a low restriction system downstream of it.

ET improvements can be found when the converter, cam and collector size are optimally tuned for one another.