Hello, I have an 83 Grand Prix with a GM 305 LG4. I was made to understand that the LG4, doesnt breathe that well, so I am considering getting headers (acutally, mostly for more meaner sound, but power too ). I have been told however, that adding headers will make the car sound alot better, but that I would lose some power, because the enigine doesnt breathe well to begin with. Only power adders I have are a K&N air cleaner, dual high flow cats and dual Flowmaster 40 series, everything else is bone stock. Does this sound right to you techies? Do you feel I would lose low end power? Thanx in advance.....

 

I lost low end on my Formula 350 with TES 1 5/8's

 

Probably because the Edelbrock headers suck on an L98.

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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=-

 

You should try to find some 1.5" headers if you don't plan on doing many more mods, but if not, look at the Heddmans. They have a 2.5" y-pipe instead of a 3" like a lot of others have, so it shouldn't hurt your low end. Overall, any headers will be a sizable improvement over the cast manifolds. If you want to do something else to augment that mod, think about an Edelbrock Performer manifold and a rebuild for your Q-jet.

I've never heard of a 1 5/8" header hurting an L98 at any rpm. Not that I'm saying it didn't happen to you. I'm just surprised.

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I lost a little on my low end on my l89 when I put on a complete SLP system, but the gains at low-mid to mid, to high were nice. It doesn't light 'em up off the line right now (bad ignition system, read my other post and reply if you can solve it please!), but about 2000-2500 RPM floored, it would suddenly start spinning 'em! I got a kick out of it...seems like my car has turbo lag off the line. Should be fixed w/ the new ignition system when I get it working though
Overall, I like the new system, it's definatly quieter than the open y-pipe it had before they went on (long story)
Corry