Think I may have finally solidified the manifold. These are made by a member of the 348-409 forum and look great. Numbers on the dyno show good also.
Stock intake ( dotted line ..... )
torque 438.5 @ 3500 RPM
horsepower 389.9 @ 5400 RPM ( 387.7 @ 5300, 387.6 @ 5500, 385.6 @ 5600, 383.4 @ 5700 )
Performer RPM intake ( broken line _ _ _ _ _ )
torque 448.7 @ 4200 RPM
horsepower 424.8 @ 5700 RPM ( 422.9 @ 5500, 424.3 @ 5600, 424.5 @ 5800, 423.9 @ 5900, 423.0 @ 6000, 421.8 @ 6100 )
Speed-Port 6000 intake ( solid line _______ )
torque 466.6 @ 4200 RPM
horsepower 465.8 @ 5800 RPM ( 464.8 @ 5600, 465.4 @ 5700, 465.7 5900, 465.7 @ 6000, 464.9 @ 6100, 464.4 @ 6200, 464.0 @ 6300 )
The also utilize the factory style PCV valve as opposed to a road draft tube.
link:
http://www.speed-port.ca/