Whata difference an H pipe made

[AZDoug]

First chassis dyno was last January, nothing changed except an H pipe was added about 6" past the collectors.

2.5" H pipe, 2.5" full exhuast, Borla mufflers, 1.62" primary pipe headers, mild hyd roller cam.

The two dyno runs are on two different scales do to adding the AFR on the same sheet as the second dyno run, but you can see the difference.

There was always a weirdness at 2000-2200 RPM before the H pipe was added, couldn't program enough fuel in, some sort of exhuast reversion. The problem disappeared with the H pipe.

Doug