Thread: Doug's Headers
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Old 03-14-2026, 06:56 PM
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Mike Davis Mike Davis is offline
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Join Date: Jun 2000
Location: Georgia
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My evac tubes are 2 inches back from collector flange at about a 30 degree angle approx 3/4in into the collector. I run a 3.5in system with x-pipe and dynomax ultra flows turned down at rear axle. The evac will work fine with free flowing or race mufflers.Big thing is to make sure the breathers fit in the grommets really tight and there are no leaks. I rtv the grommets to the valve cover and also use a ball peen hammer to tap the breather tube a little to expand. I have also found using hose clamps helps. My car runs faster with the X-pipe and evac than it does open headers or extensions. Which is surprising considering the exhaust is almost 65 lbs.

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65 GTO, Tiger Gold, Nostalgia Super Stock 421, 2-Carter AFB carbs, Stock Suspension, 3550lbs Full Exhaust-- 9.70's@135

66 GTO (Retired race car)
421 CID
Multiple NSCA/NMCA World Champion

66 GTO 389 3x2, 4 speed, 3.90 gear, Montero Red 33K original Miles
67 GTO 2dr Post, 428, Tri Power, 3.55 Gears
80 Trans Am Black SE Y84 W72 WS6
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