Well to begin, I am in the process of picking up a set of new SLP 1 5/8" headers that will be used with a set of the L98 aluminum heads. The exhaust has been seriously ported and is about 1 5/8" straight across the ports, but the L98 design is the D shape so going diagnal across the ports is 1 7/8".

So should I just keep my order with the 1 5/8" headers or should I change the order and go with the 1 3/4".

Thanks

 

It depends on what other mods you plan to do on the car. If you plan to upgrade your cam and intake, I would go with the 1 3/4". If you plan to keep the car close to stock with only external mods, I would keep the order for the 1 5/8". The 1 3/4" will take more away down low, but the gains up high will more than make up for it.

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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)

Soon to Come: 7.625" 10 Bolt with 3.42s and Accel TPI Intake Base

 

I should have been more specific, I have all aftermarket TPI components that have been extrude honed, ZZ4 cam, full MSD ignition, 3in. catback, SLP cold air, and all the other little stuff.

I ask this because I plan to go with the ZZ4 shortblock, which is only a 350. Most header company's only offer a 1 5/8" so I assumed 1 3/4" were to big. This is a street car for the most part, so down low torque is very important, more so than high end power. I only want to purcahse headers once, so if going with 1 3/4" won't make me lose a lot of bottom end, but will significantly improve the top end, I would go with them.

So basically, I am looking to get the size that will give me the most overall benefit.

Thanks

 

Go with the 1 3/4" on a 350, especially with the L98 heads special exhaust port. I have the SLP 1 3/4" on my L98 head equipped car. Our TPI cars already make a ton of torque, so dont worry about that.

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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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