Soldato
- Joined
- 13 Mar 2006
- Posts
- 6,712
They're replacement tops for the stock top, which has only a side inlet and outlet. The replacements have a top inlet and different bore inlets/outlets. They're not essential, but they give a good performace increase. See http://www.martinsliquidlab.com/DDC32PumpTopTesting.html for more details.