I have a 91z w/a dual cat 305 5-speed. I was wondering how the headers would change my exhaust note and the performance I'd pick up. I've already got the slp cat-back.

 

The TES 1 5/8" headers on my 350 gave me a good .4 reduction (faster time) in my 1/4 ET. So I bet that the SLPs 1 5/8" on your 305 should give you the same or maybe even a little better, maybe .5 off your 1/4th ET.

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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!

 

Why would the SLP's give a better ET reduction? Are you buying into all that SLP propaganda on here?

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FORMULA 350 TK
Southern California 3rd Generation F-Body Organization©

 

It probably wouldnt be noticeable on a stock 305, but I'd go with SLP on a 350. My SLP 1 5/8" headers gave me almost a .4 reduction in ET.

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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
-=ICON Motorsports=-

 

To answer the other part of the question (change in exhaust note). It may be minimal.
These header are made of thicker material, especially the stainless steel SLP's, thus not giving that traditional header sound you get with the thinner gauge metal.
By the way, it's nice to see Tom and Kevin keeping the SLP vs. TES "fued" alive. Good work, guys!
Dave Sauro

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85 calif. iroc
383/A4
9" rear

 

Heh-heh

 

Kevin, I don't know why the SLP headers won't give him much of a difference on a stock 305. My 305 TBI is still stock, but picked up over .4 seconds with just the 1-5/8 SLP header and custom Y-pipe swap.