The main reason I or most guys don't use a pipe is what size pipe to use. you use a 1 5/8 header, Joe has a 1 3/4 header, Ron has a 1 3/4, I have a 1 7/8 header, Tim has a 2 inch, and Rambo has a stepped header. On most exhaust flow test it raises the flow around 20 CFM from my testing. On this head at .500 inch lift I placed a piece of 1 5/8 plastic pipe that I had sitting here and honestly it did nothing. As long as you know whether a pipe was used is all that matters to me when I look at any flow numbers. On the intake side you HAVE to use a radius plate or some guys use clay or even duct seal. I made lexan radius plates that are universal on the bolt holes. I honestly like the ProMaxx so far and with the lack of quality done on the small block Mopar heads hope to never buy another set and I buy quite a few heads. Saying that on any serious build the exhaust side needs some shaping and should require little time.
