I was wondering if it would be more beneficial for a 305 to have odd primaires, like the Edelbrock TES with 1 5/8 and 1 1/2, or all 1 5/8. Also, would all 1 5/8's kill low end torque or is the loss minimal for the extra upper rpm breathing with equal primaires?

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86 TPI 305 Iroc-Z
700R4 (rebuilt)
Accel HEI SuperCoil
Flowmaster
K&N Filters
Comp Cams H268 218@.050 454/454 110 LSA

 

I have these on my 350 and they didn't take much away down low, and I gained lots up high. On my friend's 88 IROC 305 the TES did make equal power up high, but it took more away down low, it still netted him a .4 loss in his 1/4 ETs.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 Hot Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

7.5" 10 Bolt with 3.42s soon to come!

 

If you're keeping the 305, either header works. My opinion is the SLP headers are better, but its up to you to decide if the cost is worth it. Keep in mind the SLP headers are made from better quality stainless steel, which is why they cost more.

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
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