stevenarroyo wrote:i try to find pictures of the spark gap.
and ya i didnt add the 2 elbows into the math.
I just did a quick and dirty and it looks like you're somewhere in the 1.6-1.7:1 range. You need to account for another couple of chamber inches in your couplers on both ends as well.
Another foot or 2 on your barrel would make a noticeable difference in your performance.