I just finished installing a set of Edel. headers and y-pipe on my 83 z28 with a 305 lg4. Here are my results.

Prevous time 16.4 et at 32000ft elev. and a 200 pound passenger.
Mods- open air cleaner,MSD igniton

After header and y-pipe install:
time: 15.91 et with same passenger!

Talk about bad a** from just headers and a y. I can now shift around 5000 rpm instead of 4500 with the stock exhaust. The entire set up cost $314 after taxes from SDPC. Installation was a full weekend job though, but the quality of the setup was excellent.

 

I have to strongly agree with you. The headers are one of the best mods you can do. With a good cat back system, you will get at least another .3 or so off.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: Edelbrock TES 1 5/8" Headers, Hooker Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Components, K&N Filters, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET : 14.3 @ 97mph
(corrected for elevation)

 

When I added a set of Edelbrock headers to my Lg4 (rebuilt with a mild comp.cam) I couldn't believe the difference, it was insane. From 3000-3800 or so you could feel a decent extra pull, but much to my butt-dyno surprise I got yanked all the way to 5,500 before I hesitated like, Hhuhh? with a delayed shift. Hehheheh. Adding an Edelbrock Performer intake, an open air element, and a 3.73 rear end, and I've got myself one bad *** LG4. Mind you, it's still very much cubic inch limited.

Later.
Hype, 1983 Pontiac T/A.