Rear Bumper Parachuting
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7th Gear
Joined: Sep 2025
Posts: 7
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Rear Bumper Parachuting
Hello all. One thing I've seen a bit of recently is people who will cut "relief" holes, one on each side of the license plate to help alleviate parachuting. I am wondering if there is any data out there for impact on performance and driving? Most of the cars I've seen this done on are track cars. I'm planning on keeping my Z a street car. Not necessarily looking to cut the car up, but I am curious about the benefits. Is this a big issue with the C5, or is this one of those niche mods for minute gains that are only really worth it for the track rats out there?
Drifting
Joined: Aug 2014
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From: Virginia
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There is nothing you are going to see as a benefit for street driving. If anything could be detrimental with not enough airflow around the exhaust to keep things cool and not cause issues.
Melting Slicks
Joined: Mar 2023
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From: North Coast
GM sis SAE papers on the aero effects and the rear bumper showed great improvement if you remove the plate and open the plate are up.
The C5R car and other CR cars have opened this area up and even used it for rear differential cooling.
Now if you are racing this is an important area for you to address. But for the street don’t bother as it is not going to make a difference. It is a minute gain as you expected.
The C5R car and other CR cars have opened this area up and even used it for rear differential cooling.
Now if you are racing this is an important area for you to address. But for the street don’t bother as it is not going to make a difference. It is a minute gain as you expected.
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IMO no need to do anything.
