What OD sized tubing did you utilize? The exhaust itself looks pretty big to be honest. Are you going to grind the welds and then fully polish it? The only thing I see that might be questioned is the merged collector -- but it is really hard to tell via the camera angle. The exhaust does look good though otherwise! Post final pics when done.

The cool thing is you are taking a chance at doing something unique beside the typical enthusiasts bolt-on madness -- and I applaud you for that fact alone!