On my Edelbrock headers the air tubes stick into the exhaust pipes about 1 cm on each cylinder. Would I be helping performance by grinding them down? I hope you understand what I am talking about it is hard to explain unless you are looking at them.

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1989 Iroc-Z 5.7 350, Blue, T-Tops

Lightly Moded:
Edelbrock Headers, Rebuilt B&M 700R-4 Tranny, Higher Stall Torque Converter, Airfoil, 3.4 w\posi, K&N's, Ported Plenum
-- Blue LED Bakelite Dash & Climate Control
"Just some 17 Year old spending every dollar I make on my car."

THey stick in that much? Grind 'em back would be my vote. Major turbulence from that big an intrusion, IMHO.

I ground them back on my Edelbrocks. I can't really say how much it helped, but it couldn't have hurt anything. If you have the headers off (or not installed yet) then go for it, otherwise it might be more trouble than it's worth.

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91 Z28
Come see The Vicious...

In essence you would be helping the flow. You wouldent notice any power from making the tubes flush. If you have the headders off already then do it, if you would need to pull them off than its not worth your time.
SSC

Do it!! Those friggen tubes are a major obstruction!! I couldn't believe it when I saw them the first time. I mean they really limit the flow at one of the most critical points in the system!!!!??? I ground them all the way down (as well as the ones on the outside - no A.I.R at all on mine now) and had the holes welded shut. I then reground them flat to the primary tube and touched up the flanges a bit as well. I doubt that it will yield any measureable gain in power, but with headers with primaries that small, every little bit helps... And any power it does give you (it is more likely that it broadens the power band versus generating higher peak power figures) is free...... Can't beat free power, no matter how small it is.....

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

Matt's got it right. Those headers are so crappy in that area, anything you can do will help.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
317 RWHP, 418 RWTQ
13.23 @ 107.62 MPH (2.10 60')
Southern California
Member: SoCal 3rd Gen F-Bodies
Member: SoCal F-Bodies
-=ICON Motorsports=-

Ive seen them also I agree with Matt I would grind them down while you have them off. Also I would grind the welds inside the pipes too.

Just be Glad you didnt get SLPs. you would need a crowbar/cutting torch to get the things installed on the car.

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90 IROC
SuperRamed 406
Trickflow 23* heads

All I needed to get my SLP's in my car were a few choice cuss-words and some patience. Once I was done, I knew I had the best emissions legal headers available in my car.