Opinion about my headers

Hallo
have an LT1 383, ported heads, P1-sc 13psi twin IC, cc305, 58mmtb.
Its making 600hp at the rear wheels and 710lbft at the engine (calculated)
See the right dynosheats at these pics.
http://home.koping.net/u3243a/Tavling2004/DSC01938.JPG torque
http://home.koping.net/u3243a/Tavling2004/Åke´s%20Camaro%20Z28%20040903.jpg rwhp (slipping belt)
Thas true hooker shorties 1 5/8 and a 3.5" exhaust 3" after rear axel and a "stright true" muffler

What gains would i see with as&m 1 3/4 or slp 1 3/4 for example....

Thanks
ake

Come on, Somebody must have toughts about it.
Im planing this winters upgrades.....

IMO, gains would be minimal. If I had to guess, I would say less than 10rwhp.

thats what a reputaded engine bilder here in sweden told me....
What do you think about 3" exhaust the last 2feet? any idea to open it up to 3.5" ?
More opinions ?