PowerPipe Exhaust for slant/6

I'm guessing on s couple of variables but I ran some numbers through PipeMax and it is saying best primary size should be 1 1/2", primary tube length as close to 32" as you can (shorter is not better), collector size of 2 1/2", collector length of 20". This is for a typical 225 cid with a mild performance cam, 9.8:1, and horsepower peak around 5500. So it looks like you are close.