I am trying to figure out which header tube size is more appropriate for my set up. I currently own 1 5/8 SLP headers and 1 3/4 SLP headers. I currently have a 383 with a a cam that operates in the 2400 to 6200 rpm range, stall converter rated at 2500 rpm, TPIS mini ram intake, 52 mm throttle body. I'm not even sure if I would even notice a difference between the two headers. What is you alls opinion?

Thank you

 

1 3/4 is 1 inch of more pipe over 1 5/8.
8 X 1.75 equals 14". 8 X 1.625 equals 13".
all of this is flowing into 6" worth of collectors, which will then go to either 2.5 or 3" exhaust...usually. just a thought. personally, i'd go with which ever fit better.

 

Well they fit about equally as well. The 1 3/4 run a bit closer to the brake lines so I may have to wrap them. I'm just wondering if I could get 2 tenths of a second off my quarter mile time if I ran the 1 3/4 vs the 1 5/8. I'm thinking I probably won't see a difference in my quarter mile time with my current engine setup I just want to know what other people think before I drop this motor back in my car. Oh the exhaust goes to single 3 inch before the cat.

 

The more cam, the more compression and the better heads the bigger the headers.
And ...the higher RPM's

 

Cross sectional area is what is important for flow not diameter.

Assuming zero wall thickness:

1 5/8" = 2.07 in^2
1 3/4" = 2.41 in^2

That's 16% more flow potential. That is significant.

Since you own both, I'd use the 1 3/4" You have a health motor.