417 w/ PRC "small bore LS7" 265's... Which header?
 

So I'm in the process of putting together a 417, it's gonna be 11.7:1 with the PRC small bore LS7's. Martin had Kip grind me a 243/259 .667"/.645" 113.5+4, with Lunati/Morel 72532's spinning it to 7,2-7,500. I currently have TSP 1 3/4"x3" long tubes with really long primaries. I also have the option of running a Kooks 1 7/8"x3" setup, obviously those have considerably shorter primaries.

What's my best option here?

Big Heads, Big Cam, Big Headers! Seems no-brainer to me, at 600,
Certainly 650+ FWHP 1 3/4" starts to choke down exhaust without
Step. I imagine your shooting for 700+ with those heads and cam.
My .02

2---> 2 1/8 headers if you can fit them.

I would go ARH 1 7/8"-2" Step for N/A myself.

My goal was 550/500rw, think I'll surpass that?... I went ahead and got the 1 7/8"x3" kooks used from someone on vette forum.

Yes!!

before everyone chimes in and says you need 2.5" primarys and 4" collectors and ridiculous things like that, read this blog

http://www.exhausting101.com/?p=37


This guy has made more cars win races with proper header and exhaust design than times you have had sex in your life (okay maybe thats exaggerating, but its a lot)

Well hopefully these kooks let it breath!

Guess I was way off with my power estimate lol should be a fun street car in my C5Z...

Elston is very knowledgeable. I have followed his posts for years. Elston has stated that the first 8" or so of the header is the most important. On my LS3 heads the widest part of the exhaust port is about 1.625" or 1 5/8".

That is the inside diameter of the 1 3/4" header. That is the size my headers start out at to match the exhaust port as close as I can and be a continuation of it. Then it steps up to 1 7/8".