MACS Super Q(uiet) Marine Tuned Pipe stock # 1362 is not a performance pipe at all - It has way too much back pressure with the additional baffles inside the can.
What type of hull are you wanting to run the MAC 67 in - It makes a significant difference. One size will not fit all.
Oh ya, I am putting it in a 36" areomarine sprint cat. I think areomarin stopped making it. I know the motor might be a little much for the hull but it will be a hoot to drive. I ran a picco 67 exr in it years ago, and it was fast.
I always ran octura 455 to 457 on it.