Wow, haven't been on FF in a long time. Happy to see this out already. I had the original prototype for this system. It went through 2 modifications and took about 8 months to produce, IIRC. Because it had to get sent back after modifying and sent back here for test fitting.
Honestly, the way it is, it was a little raspy above 4500 RPMs, but I had the pipe from the header cut and had my stock cat welded up. Makes a hell of a difference. No raspy noise anymore and sounds really good. The mufflers are packed and I have been running them for 8K miles now. I get a lot of compliments and people ask if it's an ST all the time. It's definitely loud, but not loud enough to get pulled over.
Piping is 2.25"