I did two kinds of dyno runs to check out the Gibson slip on comparing it to the stock system with the tip removed.
First was a standard wide open throttle run
The second was a test I came up with which had a 25% load on and started out at 10mph to simulate being on the trail and gassing on it.
I also did a sound test, the results for the stock system with no tip was 93.5 db and the Gibson slip on what 96.5 db so there is a noticable difference.
As for power there is a .67 hp gain at peak on the standard wide open test but there was about a 2hp gain at around 50 mph.
On the loaded tested there was .90 hp gain at peak, the chart below does not show the difference in the peak on the loaded test. After about 25mph there was about a 2hp gain with the Gibson all the way thru.
No change in jetting was required, the air/fuel ratio varied only slightly from the set up from our jet kit and the stock pipe with no tip.
So the main question is, is the less than 1 hp to 2hp gain worth the price of $350 to you.
The secondary question is, would these numbers be that much different with cams or high compresion pistons? Most likely.
To view the dyno chart click the link below, then click on the full view in the upper left corner.