[Lee]

Originally Posted by wakesupremo

This is interesting reading. My 469 powered '69 convertible has run a best of 11.4 @122 mph. This was on open headers and with a 1050 dominator. A few weekends ago whilst competing in the UK street weekend i had to fit an exhaust. I have a 2.25" Borla system that is regularly on and off the car depending on what im doing with the car. I lost a second and 8 mph on the quarter. This is also with a 950 HP carb. I have been pondering the loss and was told it was the exhaust to which several people have said that it wasn't the reason. This weekend I'm doing dragstalgia on open headers so will see.

Jesus!! Your car is probably tuned very well for open headers. Choking it with a 2.25" system probably made the car run horribly rich.

Just installing better mufflers can make a big change to the AFR, requiring a change to the tune.

For pretty much any 3" system to fit GOOD, it will require an installer with the skills and equipment to make adjustments.